Compositions and methods for disrupting biofilm formation and maintenance

ABSTRACT

A method of treating a biofilm on a surface, comprising: providing a surface having a biofilm; and administering to the surface a treatment that reduces a concentration of pyruvate of the biofilm, comprising pyruvate produced by at least a portion the biofilm, under conditions effective reducing maintenance of the biofilm on the surface. A composition, comprising purified enzyme, within a particle, effective for reducing pyruvate concentration in an aqueous suspension of the composition.

CROSS REFERENCE TO RELATED APPLICATION

The present application is Division of U.S. Pat. Application No. 16/428,560, filed May 31, 2019, now U.S. Pat. No, 11,541,105, issued Jan. 3, 2023, which is a Non-provisional of, and claims benefit of priority under 35 U.S.C. § 119(e) from, U.S. Provisional Pat. Application No. 62/793,370, filed Jun. 1, 2018, the entirety of which are expressly incorporated herein by reference.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support under 1R56AI127815 awarded by the National Institutes of Health. The government has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates to compositions and methods for treating biofilms and infections associated with biofilms, and disrupting biofilm formation and maintenance.

BACKGROUND OF THE INVENTION

Each reference cited herein is expressly incorporated herein in its entirety.

Biofilms are surface-associated bacterial communities that are matrix-encased, and may cause persistent and chronic infections in medical settings. Biofilm-related infections include chronic urinary tract infection due to catheters, chronic wounds (e.g., diabetic, burn, surgical), ventilated-associated pneumonia in intubated patients, chronic pulmonary disease in patients with cystic fibrosis or chronic obstructive lung disease. According to the National Institutes of Health, 65 percent of all hospital-acquired infections are due to bacteria growing as biofilms, and 80 percent of chronic infections are linked to biofilms. To put this in perspective, the Center for Disease Control estimates that hospital-acquired infections account for an estimated 1.7 million infections and 99,000 associated deaths each year in American hospitals alone. The high morbidity and mortality rate is due to biofilms being extremely difficult to control in medical settings. In fact, conventional therapies have proven inadequate in the treatment of many (if not most) chronic biofilm infections, due to the extraordinary tolerance of biofilms to available antimicrobial agents relative to their planktonic counterparts, and their ability to inhibit healing.

A hallmark of biofilms is their extreme tolerance to antimicrobial agents, rendering infections by biofilms recalcitrant to conventional treatment therapies. This has brought on the realization that successful treatment of biofilm infections will require the development of novel treatment strategies. It is thus not surprising that biofilm dispersion, a regulatory response to environmental cues, allowing bacterial cells to convert to the planktonic state, has become a major focus of recent research endeavors to combat biofilms. However, while much attention has been paid to agents inducing biofilm dispersion, little is known about the mechanism underlying dispersion. P. aeruginosa has been previously shown to require autogenously produced pyruvate and pyruvate fermentative processes as a means of redox balancing to form microcolonies, with depletion of pyruvate or inactivation of components of the pyruvate fermentation pathway impairing biofilm formation (See FIG. 1 ). Olga E. Petrova, Jill R. Schurr, Michael J. Schurr, and Karin Sauer, Microcolony formation by the opportunistic pathogen Pseudomonas aeruginosa requires pyruvate and pyruvate fermentation, Molecular Microbiology (2012) 86(4), 819-835, doi:10.1111 /mmi.12018.

Bacterial infections are common complication of burn wounds, with surface-associated communities of bacteria known as biofilms forming within human burn wounds within 10-24 hr. of thermal injury. The presence of biofilms in burns is problematic as biofilms are recalcitrant to killing by antimicrobial agents, thus rendering conventional treatment strategies ineffective, with 75% of extensively burned patients dying as a consequence of severe infection.

Cells associated with biofilms are up to 1000-fold less susceptible to various antibiotics than their planktonic counterparts. For instance, the development of antimicrobial burn creams was considered a major advance in the care of burn wound patients, yet infections of wounds remain the most common cause of morbidity and mortality among the 6.5 million people suffering from wounds in the United States alone, causing over 200,000 deaths annually. The most affected are people suffering from burn wounds, for which almost 61% of deaths are caused by infection. Treatment failure has been primarily attributed to the virulence factors produced by the principal wound pathogens Staphylococcus aureus and Pseudomonas aeruginosa as well as their ability to form biofilms in wounds, which are recalcitrant to antibiotic treatment and the host immune defense.

Pseudomonas aeruginosa is responsible for a wide array of persistent infections including those of non-healing wounds and the lungs of cystic fibrosis sufferers. Within the cystic fibrosis lung, P. aeruginosa forms biofilms, defined as complex surface-attached communities encased in an extracellular matrix composed of exopolysaccharides, DNA and proteins. A hallmark of P. aeruginosa biofilms is the presence of complex multicellular aggregates or microcolonies, the formation of which has been observed both in vitro and in vivo (Lam et al., 1980; Høiby et al., 2001; Sauer et al., 2002; Davey et al., 2003; Garcia-Medina et al., 2005; Sriramulu et al., 2005) and has been associated with DNA release and elevated mutation rates (Allesen-Holm et al., 2006; Conibear et al., 2009). Iron has been demonstrated to control microcolony formation, as P. aeruginosa mutants inactivated in the high-affinity pyoverdine iron acquisition system only form thin unstructured biofilms even when grown in iron-sufficient medium (Banin et al., 2005). While the findings implicated iron as a signal for development of mushroom-like microcolonies, Yang et al. (2007) demonstrated microcolony formation to be favored in media with low iron availability, with increasing iron concentrations resulting in decreased microcolony formation and DNA release. Microcolony formation coincides with the formation of steep oxygen and nutrient gradients, with cells located deep within biofilm structures experiencing stressful, growth-limiting conditions (Anderl et al., 2003; Walters et al., 2003; Borriello et al., 2004). Microelectrode analyses have revealed that, while the concentration of oxygen at the surface of the biofilm is similar to that of the bulk fluid, oxygen levels drop rapidly towards the interior of biofilms with the center of microcolonies being essentially anaerobic (de Beer et al., 1994; Stoodley et al., 1994; 1997; Rasmussen and Lewandowski, 1998; Rani et al., 2007). Additional gradients exist in the biofilm environment with respect to microbial waste products, sulphide and hydrogen ions (pH), which may accumulate within the depths of the biofilm (de Beer et al., 1994; Stoodley et al., 1994; 1997; Rasmussen and Lewandowski, 1998; Raniet al., 2007).

The resident bacterial population has been demonstrated to adjust to these steep gradients through various approaches including the modulation of metabolic rates, dormancy, stress responses and mutation rates (Stewart, 1996; Anderl et al., 2000; Walters et al., 2003; Borriello et al., 2004; Lenz et al., 2008; Pérez-Osorio et al., 2010). Selected metabolic pathways have been associated with biofilm formation, serving both as contributing factors and adaptations to the changing biofilm microenvironment. For instance, availability of amino acids appears to contribute to biofilm formation, as inactivation of the stationary phase sigma factor RpoS has been shown to enhance biofilm formation by alleviating potential amino acid limitation (Shirtliff et al., 2002). Inactivation of the catabolite repression control (Crc) protein, involved in carbon metabolism regulation and control of type IV pili gene expression, resulted in the formation of cellular monolayers devoid of microcolonies typically observed during normal biofilm development (O’Toole et al., 2000). Furthermore, under conditions of oxygen absence or limitation, P. aeruginosa is able to respire nitrate or nitrite through the process of denitrification, which sequentially reduces nitrate to nitrogen gas through the action of four reductases (Carlson et al., 1982; Carlson and Ingraham, 1983; Davies et al., 1989). The activation/upregulation of the components of the denitrification pathway has been repeatedly observed within in vitro biofilms and during persistent P. aeruginosa infections, with sensing and processing of nitrate and other intermediate forms playing an essential role in the establishment, maintenance, resistance and dispersal of biofilms in vitro and in vivo (Hassett et al., 2002; 2009; Borriello et al., 2004; Barraud et al., 2006; Filiatrault et al., 2006; Alvarez-Ortega and Harwood, 2007; Toyofuku et al., 2007; Van Alst et al., 2007; Schobert and Jahn, 2010). Many environments, however, do not have sufficient nitrate present to drive nitrate respiration. Under conditions of oxygen limitation in the absence of nitrate, growth is driven by oxygen respiration, done using high-affinity terminal oxidases including cbb3-1 and cbb3-2 (Comolli and Donohue, 2004; Alvarez-Ortega and Harwood, 2007).

UspK has been previously shown to be essential for survival on pyruvate under conditions of oxygen limitation (Schreiber et al., 2006), with P. aeruginosa PA14 being able to release pyruvate, using a pyocyanin-dependent mechanism, and subsequently utilize pyruvate during stationary phase (Price-Whelan et al., 2007). Genes associated with pyruvate fermentation are downregulated in mifR mutant biofilms (Tables 3 and S4), pyruvate utilization contributes to biofilm formation and the establishment of microcolonies. Exogenously added pyruvate supports biofilm development in wild type PA14 biofilms. Addition of pyruvate (0.1-1 mM) to the growth medium (diluted LB medium) resulted in enhanced microcolony formation by wild type biofilms with the average diameter of microcolonies increasing 1.6-fold in the presence of 1 mM pyruvate. Addition of 1 mM pyruvate did not enhance growth of P. aeruginosa grown planktonically under fully aerated conditions. However, the presence of 25 mM pyruvate as the sole carbon source supported some growth by P. aeruginosa.

As increased availability of pyruvate coincided with enhanced microcolony formation, when grown in LB or VBMM medium, lack of pyruvate abrogates microcolony formation by enzymatically depleting pyruvate from the growth medium using pyruvate dehydrogenase (PDH). Under the conditions tested, the presence of pyruvate dehydrogenase and the appropriate cofactors (CoA, NADH) did not affect growth in broth when grown in microtiter plates, as determined by absorbance (not shown). However, presence of PDH during the early stages of biofilm development impaired microcolony formation, with PDH-treated biofilms containing infrequent thin and unstructured clusters not exceeding 20 µm in diameter. In contrast, biofilms treated with heat-inactivated PDH or cofactors alone were similar to untreated biofilms and characterized by widespread microcolonies exceeding 150 µm in diameter.

The findings strongly supported a requirement for pyruvate in the process of biofilm microcolony formation regardless of medium used.

NADH-dependent lactate dehydrogenase LdhA has been previously shown to be required for anaerobic pyruvate utilization and long-time survival on pyruvate (Eschbach et al., 2004). In addition, aconitate hydratase AcnA, plays a role in tricarboxylic acid cycle, glyoxylate bypass and acetyl-CoA assimilation (and only indirectly in pyruvate utilization) (Somerville et al., 1999; Winsor et al., 2009). Inactivation of acnA resulted in impaired biofilm formation as indicated by biofilms being characterized by up to 10-fold reduced biofilm biomass and thickness as compared to wild type biofilms. Complementation restored biofilm formation to wild type levels. Similarly, expression of mifR in the acnA mutant did result in significantly enhanced biofilm and microcolony formation, with parameters including biomass and thickness increasing more than fourfold when compared to the acnA mutant alone. These suggest that, while AcnA contributes to biofilm formation, AcnA acts downstream of MifR and is probably not the direct cause of the MifRor pyruvate-dependent microcolony formation phenotypes. This is in part based on the finding of AcnA being required not only for pyruvate utilization but also for the tricarboxylic acid cycle, glyoxylate bypass and acetyl-CoA assimilation.

Inactivation of ldhA resulted in fourfold reduced biofilm biomass accumulation and reduced thickness while complementation restored biofilm formation to wild type levels. Overall, the architecture of ldhA mutant biofilms was similar to that observed for mifR mutant biofilms and was only composed of small clusters less than 20 µm in diameter. Furthermore, in contrast to the results observed for acnA::Mar, expression of mifR in ldhA mutant biofilms failed to restore biofilm and microcolony formation to wild type levels, with ldhA::Mar/pMJT-mifR demonstrating the same biofilm architecture as the ldhA mutant. This supports a role for LdhA and pyruvate fermentation in microcolony formation.

Exogenous pyruvate and lactate dehydrogenase, associated with pyruvate utilization under limited-oxygen conditions, are required for microcolony formation. The ldhA mutant did not respond to the addition of pyruvate (grown in diluted LB), with the strain demonstrating similar defects in biofilm formation in the absence and presence of exogenous pyruvate. Similar results were obtained when VBMM medium was used. Expression of ldhA in PA14, while not increasing the overall biofilm biomass, correlated with a significant increase in microcolony formation. The increase in microcolony formation was comparable to the increase observed upon pyruvate addition. Expression of ldhA in mifR mutant biofilms fully restored the biofilm architecture to wild type levels, resulting in a significant increase in biofilm biomass accumulation and more importantly, the formation of microcolonies exceeding >150 µm in diameter. To determine whether ldhA mutant biofilms demonstrated a significantly increased NADH/NAD+ ratio compared to wild type, while overexpression of ldhA significantly decreased the available NADH as indicated by a decreased NADH/NAD+ ratio compared to wild type biofilms. There is thus an inverse correlation between NADH/NAD+ ratio and microcolony formation. The presence of pyocyanin has been demonstrated to alter NADH/NAD+ ratios (Price-Whelan et al., 2007).

Differential expression of ldhA resulted in an overall similar trend with respect to NADH/NAD+ ratios as those obtained under biofilm growth conditions, with ldhA mutant demonstrating increased NADH/NAD+ ratios and overexpression of ldhA correlating with decreased NADH/NAD+ ratios compared to wild type. Inactivation of mifR resulted in significantly increased NADH/NAD+ ratio compared to wild type, while expression of mifR or ldhA in mifR mutants restored the NADH/NAD+ ratio to wild type levels. There is thus a requirement for pyruvate in biofilm microcolony formation, with the observed effects likely being mediated via the pyruvate fermentation pathway, probably as a means of redox balancing.

P. aeruginosa is capable of fermentatively utilizing pyruvate for survival under conditions of oxygen limitation in the absence of nitrite and nitrate (Eschbach et al., 2004; Schreiber et al., 2006). The process involves the conversion of pyruvate to lactate, acetate and/or succinate, with the lactate and acetate-producing branches of the pathway apparently predominating. Inactivation of lactate dehydrogenase (LdhA), which converts pyruvate to lactate and regenerates NAD+, severely impairs pyruvate fermentation and compromises survival on pyruvate under conditions of energy (electron) richness (Eschbach et al., 2004). Pyruvate does not support growth under strictly anaerobic growth conditions. Moreover, while addition of 0.1-1 mM of pyruvate to 24-well grown P. aeruginosa is not sufficient to increase growth, higher concentrations of pyruvate are capable of sustaining growth under aerobic and oxygen limiting (but not anaerobic) conditions. Pyruvate therefore appears to be used as a means of redox balancing. Consistent with a role of LdhA in regenerating reducing equivalents under oxygen-limiting conditions, expression of LdhA in P. aeruginosa wild type correlated with a significant increase in biofilm biomass accumulation and microcolony formation as well as restoration of the mifR mutant biofilm phenotype to wild type levels and decreased NADH/NAD+ ratios. Redox balancing appears required to enable microcolony formation in biofilms.

Pyruvate appears to be produced by the resident biofilm bacteria. A model recently proposed by Schobert and Jahn (2010) places P. aeruginosa biofilm cells within different niches, with metabolically active cells exposed to oxygen secreting pyruvate, which then diffuses into the anoxic zones to be utilized by cells residing within these layers. Consistent with this model is the pyruvate-dependent formation of microcolonies, with depletion of extracellular pyruvate impairing biofilm development and abrogating microcolony formation, while addition of exogenous pyruvate enhances biofilm development by specifically promoting microcolony formation. Pyruvate is released into the extracellular environment by P. aeruginosa PA14 during stationary phase in a manner dependent on the redox-active phenazine pyocyanin (Price-Whelan et al., 2007). Although phenazine production does not impact the ability of P. aeruginosa PA14 to attach to surfaces, mutants unable to synthesize phenazines including pyocyanin were impaired in microcolony formation (Dietrich et al., 2008; Ramos et al., 2010). Moreover, P. aeruginosa PA14 differs from PAO1 with respect to pyocyanin levels with PA14 producing more pyocyanin than PAO1 (Dietrich et al., 2006) as well as secreting more pyruvate (Price-Whelan et al., 2007). Increased pyocyanin and pyruvate release correlates with observation of P. aeruginosa PA14 biofilms forming significantly larger microcolonies following 6 days of growth under continuous flowing conditions and earlier initiation of microcolony formation compared to PAO1.

Usp proteins, which are conserved across all domains of life, have been implicated in the response to hypoxic conditions and establishment of chronic, persistent infections by Mycobacterium tuberculosis (Drumm et al., 2009), stress-mediated adhesion and motility in Escherichia coli (Nachin et al., 2005) and the process of biofilm formation by Porphyromonas gingivalis (Kuramitsu et al., 2005; Chen et al., 2006). In P. aeruginosa, increased expression of all five Usp proteins has been consistently observed under conditions of oxygen limitation, in laboratory-grown biofilms (Yoon et al., 2002; Waite et al., 2006; Alvarez-Ortega and Harwood, 2007), and in the context of in vivo infections (Mashburn et al., 2005; Bielecki et al., 2011). Usp proteins enable anaerobic growth and/or survival of P. aeruginosa, with inactivation of uspN and uspK having been linked to premature cell death during long-term anaerobic existence (Eschbach et al., 2004; Boes et al., 2006; Schreiber et al., 2006). However, UspN and UspK do so via distinct rather than converging mechanisms. UspN is required for survival when cells experience anaerobic energy stress and starvation, with a mutant strain demonstrating significantly reduced cell recovery after prolonged exposure to such conditions (Boes et al., 2006; 2008), while UspK is essential for P. aeruginosa anaerobic survival via pyruvate fermentation (Eschbach et al., 2004; Schreiber et al., 2006). This difference in mechanisms was apparent with respect to microcolony formation. The small biomass accumulation defect observed following UspN inactivation suggests that subpopulations of biofilm cells experiencing anaerobic energy starvation likely utilize systems such as UspN to promote survival. In contrast, inactivation of UspK resulted in severely reduced microcolonies and biomass, strongly supporting a requirement for UspK in microcolony formation. Given that UspK plays a substantial role during fermentative growth on pyruvate, but is not required for denitrification (Schreiber et al., 2006), these findings strongly underscore the requirement for pyruvate fermentation as a means of addressing oxygen limitation of the biofilm microcolony microenvironment and the need for redox balancing.

Bacteria present within microcolonies experience an environment that is distinct from environmental conditions elsewhere in the biofilm. Within microcolonies, P. aeruginosa cells experience low oxygen but energy (electron)-rich conditions and use fermentative processes for survival and growth. In particular, pyruvate is required for microcolony formation by P. aeruginosa with changes in extracellular pyruvate levels positively correlating with average biofilm cellular aggregate sizes. Pyruvate contributes to growth of biofilm microcolonies via pyruvate fermentation as a means of redox balancing with inactivation of lactate dehydrogenase preventing biofilm development and microcolony formation.

Pyruvate dehydrogenase is the enzyme that catalyzes conversion of pyruvate to acetyl-CoA and NADH, with an intermediate decarboxylation, in the presence of CoA and NAD+. Thiamine phosphate (TPP) is required for pyruvate dehydrogenase activity, but TPP is not involved in the biochemical reaction. See FIG. 18 , which represents various standard biochemical pathways involving pyruvate.

P. aeruginosa produces and secretes up to 10 mM pyruvate, with pyruvate having been shown to be required for long-term bacterial survival (without serving as a carbon source).

Pyruvate plays an essential role in the formation of biofilms, as continuous depletion of pyruvate (via pyruvate dehydrogenase [PDH, 0.57 U/mg specific activity] plus cofactors) from the growth medium prevented biofilm formation. Pyruvate is required to cope with stressful, oxygen-limiting but electron-rich conditions, referred to as ‘reductive stress’ (too much NADH/electrons, not enough O₂) present in biofilms. This is apparent by the activation of pyruvate fermentation pathways in biofilms, and mutant strains inactivated in genes involved in pyruvate fermentation, including acnA and ldhA encoding aconitase and lactate dehydrogenase, respectively, being unable to form biofilms.

Dispersion is a regulated process by which biofilm bacteria liberate themselves from the matrix-encased biofilms and transition to the planktonic, free-living state that is less protected from the immune system, and more susceptible to antimicrobial agents.

To maintain their three-dimensional, aggregated structure, biofilms require pyruvate to cope with the stressful, oxygen-limiting but electron-rich conditions.

Pyruvate dehydrogenase (acyl transferring) (e.g., E.C. 1.2.4.1) is the first component enzyme of pyruvate dehydrogenase complex (PDC)(E.C. 2.3.1.12 and E.C. 1.8.1.4). The pyruvate dehydrogenase complex contributes to transforming pyruvate into acetyl-CoA by a process called pyruvate decarboxylation. Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, so pyruvate dehydrogenase contributes to linking the glycolysis metabolic pathway to the citric acid cycle and releasing energy via NADH. The pyruvate decarboxylase (PDC) mechanism with pyruvate (R = H) is shown in FIG. 19 .

Formally, the reaction catalyzed is

pyruvate + [dihydrolipoyllysine-residue acetyltransferase] lipoyllysine → [dihydrolipoyllysine-residue acetyltransferase] S-acetyldihydrolipoyllysine + CO2

Other names for this enzyme are: MtPDC (mitochondrial pyruvate dehydrogenase complex); pyruvate decarboxylase; pyruvate dehydrogenase; pyruvate dehydrogenase (lipoamide); pyruvate dehydrogenase complex; pyruvate:lipoamide 2-oxidoreductase (decarboxylating and acceptor-acetylating); pyruvic acid dehydrogenase; pyruvic dehydrogenase.

See, Ochoa, S. Enzymic mechanisms in the citric acid cycle. Adv. Enzymol. Relat. Subj. Biochem. 15 (1954) 183-270; Scriba, P. and Holzer, H. Gewinnung von αHydroxyäthyl-2-thiaminpyrophosphat mit Pyruvatoxydase aus Schweineherzmuskel. Biochem. Z. 334 (1961) 473-486; Perham, R.N. Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions. Annu. Rev. Biochem., 69, (2000) 961-1004. [PMID: 10966480], www.sbcs.qmul.ac.uk/iubmb/enzyme/EC1/2/4/l.html; en.wikipedia.org/wiki/Pyruvate_dehydrogenase; en.wikipedia.org/wiki/Pyruvate_dehydrogenase_complex.

In Gram-negative bacteria, e.g., Escherichia coli, PDC consists of a central cubic core made up from 24 molecules of dihydrolipoyl transacetylase (E2). Up to 24 copies of pyruvate dehydrogenase (E1) and 12 molecules of dihydrolipoyl dehydrogenase (E3) bind to the outside of the E2 core. In contrast, in Gram-positive bacteria (e.g. Bacillus stearothermophilus) and eukaryotes the central PDC core contains 60 E2 molecules arranged into an icosahedron. Eukaryotes also contain 12 copies of an additional core protein, E3 binding protein (E3BP). Up to 60 E1 or E3 molecules can associate with the E2 core from Gram-positive bacteria binding is mutually exclusive. In eukaryotes E1 is specifically bound by E2, while E3 associates with E3BP. It is thought that up to 30 E1 and 6 E3 enzymes are present, although the exact number of molecules can vary in vivo and often reflects the metabolic requirements of the tissue in question.

Pyruvate dehydrogenase (E1) performs the first two reactions within the pyruvate dehydrogenase complex (PDC): a decarboxylation of substrate 1 (pyruvate) and a reductive acetylation of substrate 2 (lipoic acid). Lipoic acid is covalently bound to dihydrolipoamide acetyltransferase (E2), which is the second catalytic component enzyme of PDC. The reaction catalyzed by pyruvate dehydrogenase (E1) is considered to be the rate-limiting step for the pyruvate dehydrogenase complex (PDHc). See FIG. 19 .

Phosphorylation of E1 by pyruvate dehydrogenase kinase (PDK) inactivates E1 and subsequently the entire complex. PDK is inhibited by dichloroacetic acid and pyruvate, resulting in a higher quantity of active, unphosphorylated PDH. Phosphorylation is reversed by pyruvate dehydrogenase phosphatase, which is stimulated by insulin, PEP, and AMP, but competitively inhibited by ATP, NADH, and Acetyl-CoA.

The ylide resonance form of thiamine pyrophosphate (TPP) begins by attacking the electrophilic ketone of pyruvate. See FIG. 20 . The intermediate β-alkoxide then decarboxylates and the resulting enol is deprotonated on the carbon atom to form a stabilized 1,3-dipole involving a positively charged nitrogen atom of the thiamine heterocycle. This 1,3-dipole undergoes a reductive acetylation with lipoamide-E2.

Biochemical and structural data for E1 revealed a mechanism of activation of TPP coenzyme by forming the conserved hydrogen bond with glutamate residue (Glu59 in human E1) and by imposing a V-conformation that brings the N4′ atom of the aminopyrimidine to intramolecular hydrogen bonding with the thiazolium C2 atom. This unique combination of contacts and conformations of TPP leads to formation of the reactive C2-carbanion, eventually. After the cofactor TPP decarboxylates pyruvate, the acetyl portion becomes a hydroxyethyl derivative covalently attached to TPP.

E1 is a multimeric protein. Mammalian E1s, including human E1, are tetrameric, composed of two αand two βsubunits. Some bacterial E1s, including E1 from Escherichia coli, are composed of two similar subunits, each being as large as the sum of molecular masses of αand βsubunits.

E1 has two catalytic sites, each providing thiamine pyrophosphate (TPP) and magnesium ion as cofactors. The αsubunit binds magnesium ion and pyrophosphate fragment while the β-subunit binds pyrimidine fragment of TPP, forming together a catalytic site at the interface of subunits.

Initially, pyruvate and thiamine pyrophosphate (TPP or vitamin B1) are bound by pyruvate dehydrogenase subunits. The thiazolium ring of TPP is in a zwitterionic form, and the anionic C2 carbon performs a nucleophilic attack on the C2 (ketone) carbonyl of pyruvate. The resulting hemithioacetal undergoes decarboxylation to produce an acyl anion equivalent (see cyanohydrin or aldehyde-dithiane umpolung chemistry, as well as benzoin condensation). This anion attacks S1 of an oxidized lipoate species that is attached to a lysine residue. In a ring-opening SN2-like mechanism, S2 is displaced as a sulfide or sulfhydryl moiety. Subsequent collapse of the tetrahedral hemithioacetal ejects thiazole, releasing the TPP cofactor and generating a thioacetate on S1 of lipoate. The E1-catalyzed process is the rate-limiting step of the whole pyruvate dehydrogenase complex.

At this point, the lipoate-thioester functionality is translocated into the dihydrolipoyl transacetylase (E2) active site, where a transacylation reaction transfers the acetyl from the “swinging arm” of lipoyl to the thiol of coenzyme A. This produces acetyl-CoA, which is released from the enzyme complex and subsequently enters the citric acid cycle. E2 can also be known as lipoamide reductase-transacetylase.

The dihydrolipoate, still bound to a lysine residue of the complex, then migrates to the dihydrolipoyl dehydrogenase (E3) active site where it undergoes a flavin-mediated oxidation, identical in chemistry to disulfide isomerase. First, FAD oxidizes dihydrolipoate back to its lipoate resting state, producing FADH2. Then, a NAD+ cofactor oxidizes FADH2 back to its FAD resting state, producing NADH.

The reaction tends to be irreversible, for example because of the decarboxylation. The enzyme has a high substrate affinity, and therefore can reduce pyruvate to very low levels.

Pyruvate can also be specifically depleted using other enzymes such as lactate dehydrogenase (LDH) that catalyzes the conversion of pyruvate (plus NADH) to lactate and NAD+. Pyruvate carboxylase catalyzes the conversion of pyruvate and CO₂ to oxaloacetate, but is ATP dependent. Alanine transaminase produces alanine from pyruvate, and glutamate to α-ketoglutarate, in a reversible reaction. Pyruvate decarboxylase is TPP dependent, and produces acetaldehyde and CO₂. E. coli has a pyruvic formate lyase enzyme that catalyzes the reaction acetyl-CoA + formate = CoA + pyruvate.

Other enzymes are available that degrade pyruvate, such as pyruvate oxidase (en.wikipedia.org/wiki/Pyruvate_oxidase)(EC 1.2.3.3) is an enzyme that catalyzes the reaction:

The 3 substrates of this enzyme are pyruvate, phosphate, and O₂, whereas its 3 products are acetyl phosphate, CO₂, and H₂O₂. This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with oxygen as acceptor. It has 2 cofactors: FAD, and Thiamin diphosphate.

See, Caiazza NC, O’Toole GA. 2004. SadB is required for the transition from reversible to irreversible attachment during biofilm formation by Pseudomonas aeruginosa PA14. J. Bacteriol. 186:4476-4485.

Models of biofilm formation by Pseudomonas aeruginosa propose that (i) planktonic cells become surface associated in a monolayer, (ii) surface-associated cells form microcolonies by clonal growth and/or aggregation, (iii) microcolonies transition to a mature biofilm comprised of exopolysaccharide-encased macrocolonies, and (iv) cells exit the mature biofilm and reenter the planktonic state.

Pseudomonas aeruginosa is a model organism for studying biofilm formation in gram-negative bacteria. Planktonic (free-swimming) P. aeruginosa initiates surface colonization in a flagellum-dependent manner, then forms transient (“reversible”) surface interactions, and subsequently becomes firmly (“irreversibly”) attached. It has been recently demonstrated for P. fluorescens that an ABC transporter and a large secreted protein are necessary for irreversible attachment by this organism. The earliest events in the pathway whereby planktonic bacteria form surface-associated microbial communities are unclear; however, it is clear that bacteria sample surface niches via reversible attachment before taking up permanent residence. This commitment to irreversible attachment is a crucial step in biofilm formation because initial surface colonizers are likely the foundation upon which the mature biofilm will be built. After irreversibly attaching, P. aeruginosa proceeds to form microcolonies in a type IV pilus and a GacA-dependent manner. As microcolonies become matrix-enclosed macrocolonies, cell-to-cell signaling is thought to become increasingly important. It has been proposed that this transition from a planktonic to a biofilm lifestyle is a developmental process.

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U.S. Pat. App. 20130302390; 20130216637; 20080317815; 20070207095.

Dispersion inducers and quorum sensing factors may include various factors, such as ATP, c-di-GMP, other cyclic nucleotides, cis-2-decenoic acid, Skyllamycins A to C, nitric oxide, diphenyl selenide, etc.

Known antimicrobial agent include (poly)peptides, amikacin, aminoglycosides, amoxicillin, amoxicillin/clavulanate, amphotericin B, ampicillin, ampicillin-sulbactam, anidulafungin, ansamycins, arsphenamine, azithromycin, azlocillin, aztreonam, bacitracin, bacteriocins, bismuth thiols, carbacephems, carbapenems, carbenicillin, caspofungin, cefaclor, cefadroxil, cefalotin, cefamandole, cefazolin, cefdinir, cefditoren, cefepime, cefixime, cefoperazone, cefotaxime, cefoxitin, cefpodoxime, cefprozil, ceftaroline, ceftazidime, ceftibuten, ceftizoxime, ceftobiprole, ceftriaxone, cefuroxime, cephalexin, cephalosporins, chloramphenicol, ciprofloxacin, clarithromycin, clindamycin, clofazimine, cloxacillin, colicins, colistin, dalbavancin, daptomycin, demeclocycline, dicloxacillin, dirithromycin, doripenem, doxycycline, enoxacin, ertapenem, erythromycin, ethambutol, fecluroxime, flucloxacillin, fluconazole, flucytosine, fosfomycin, furazolidone, gatifloxacin, gemifloxacin, gentamicin, glycopeptides, grepafloxacin, imipenem, imipenem/cilastatin, isoniazid, itraconazole, kanamycin, ketoconazole, levofloxacin, lincomycin, lincosamides, linezolid, lomefloxacin, loracarbef, macrolides, mafenide, meropenem, metronidazole, mezlocillin, micafungin, microcins, minocycline, moxifloxacin, mupirocin, nafcillin, naldixic acid, neomycin, netilmicin, nitrofurans, nitrofurantoin, norfloxacin, ofloxacin, oritavancin, oxazolidinones, oxycycline, oxytetracycline, paromomycin, penicillins, piperacillin, piperacillin-tazobactam, polymyxin B, polypeptides, posaconazole, posizolid, prontosil, pyrazinamide, quinolones, quinupristin/dalfopristin, radezolid, rifampicin, rifampin, rifaximin, roxithromycin, sparfloxacin, spectinomycin, spiramycin, streptomycin, suflonamides, sulfacetamide, sulfadiazine, sulfadimethoxine, sulfamethizole, sulfamethoxazole, sulfasalazine, sulfisoxazole, sulfonamides, teicoplanin, telavancin, telithromycin, temafloxacin, tetracyclines, ticarcillin, ticarcillin/clavulanate, tigecycline, tobramycin, torezolid, trimethoprim, trimethoprim-sulfamethoxazole, trovafloxacin, vancomycin, and voriconazole.

Known antibiofilm agents include: 6086921; 6106854; 6248371; 6641739; 6692757; 6793900; 6887270; 6908912; 7025986; 7052614; 7087661; 7144992; 7147888; 7151139; 7189329; 7189351; 7201925; 7217425; 7255881; 7314857; 7399742; 7402722; 7419607; 7427416; 7446089; 7450228; 7452345; 7556807; 7601731; 7628929; 7691418; 7744555; 7760353; 7781166; 7790947; 7794698; 7829305; 7863029; 7897631; 7906544; 7927496; 7993390; 7998919; 8071540; 8076117; 8105520; 8133501; 8142764; 8153119; 8153410; 8153412; 8162924; 8168072; 8173673; 8211361; 8216173; 8227017; 8231686; 8236545; 8246691; 8257827; 8267883; 8273104; 8278340; 8282593; 8282967; 8309590; 8318180; 8329758; 8343086; 8343911; 8349368; 8366652; 8367713; 8367716; 8367823; 8377455; 8383101; 8383582; 8389021; 8389679; 8398705; 8399235; 8399649; 8414517; 8415159; 8425880; 8431151; 8444858; 8460229; 8460916; 8461106; 8476425; 8481138; 8486428; 8501969; 8507244; 8545951; 8546121; 8552147; 8552208; 8569449; 8574660; 8585627; 8591876; 8591961; 8592473; 8609110; 8617523; 8617542; 8618149; 8623340; 8632838; 8637090; 8641686; 8647292; 8652829; 8653124; 8658225; 8680072; 8680148; 8684732; 8685427; 8685957; 8691264; 8697102; 8697375; 8702640; 8706211; 8709342; 8710082; 8715733; 8728467; 8734718; 8741855; 8753304; 8753692; 8754039; 8758781; 8778370; 8778387; 8778889; 8779023; 8785399; 8795727; 8796252; 8802059; 8802414; 8808718; 8809031; 8809314; 8821862; 8821910; 8828910; 8829053; 8835644; 8840912; 8846008; 8846009; 8846605; 8852912; 8853278; 8865909; 8884022; 8888731; 8889196; 8906349; 8906364; 8906393; 8906898; 8906915; 8920826; 8926951; 8927029; 8940911; 8945142; 8952192; 8956658; 8956663; 8962029; 8962283; 8968753; 8968765; 8981139; 8992223; 8999265; 9005263; 9005643; 9028878; 9029318; 9034346; 9034927; 9044485; 9045550; 9056899; 9073884; 9078441; 9084423; 9085608; 9096703; 9125408; 9125853; 9139622; 9145395; 9149648; 9150453; 9156855; 9161923; 9161984; 9167820; 9169319; 9180157; 9180158; 9181290; 9187501; 9198957; 9220267; 9221765; 9221875; 9227980; 9242951; 9247734; 9253987; 9265820; 9271493; 9271502; 9273096; 9283283; 9284351; 9289442; 9289449; 9295257; 9308298; 9320740; 9321030; 9326511; 9326924; 9326925; 9334466; 9339525; 9351491; 9351492; 9358274; 9364491; 9370187; 9376430; 9387189; 9402394; 9403851; 9403852; 9408393; 9415144; 9423532; 9427605; 9433527; 9439433; 9439436; 9439803; 9446090; 9452107; 9469616; 9474831; 9480260; 9480541; 9487453; 9492596; 9499594; 9504688; 9504739; 9518013; 9526738; 9526766; 9539233; 9539367; 9539373; 9540471; 9550005; 9554971; 9556109; 9556223; 9561168; 9562085; 9562254; 9565857; 9566247; 9566341; 9566372; 9574185; 9586871; 9592299; 9592324; 9597407; 9603859; 9603877; 9603977; 9603979; 9612246; 9617176; 9622481; 9631100; 9642829; 9644194; 9648876; 9657132; 9669001; 9669041; 9675077; 9675736; 9682023; 9683197; 9687670; 9694114; 9700058; 9700650; 9706778; 9713631; 9713652; 9717251; 9717765; 9718739; 9723833; 9723837; 9723843; 9724353; 9732124; 9737561; 9737571; 9737591; 9744270; 9757397; 9764069; 9770418; 9777050; 9782388; 9782423; 9789005; 9795762; 9801982; 9808496; 9814719; 9815794; 9833528; 9834744; 9839219; 9849182; 9850322; 9854807; 9855211; 9856225; 9861701; 9861723; 9862837; 9867906; 9872491; 9872893; 9872906; 9872917; 9877983; 9889077; 9895469; 9907584; 9914750; 9918473; 9919012; 9919072; 9919079; 9926526; 9931300; 9931381; 9932484; 9937104; 9956319; 9956322; 9975857; 20020066702; 20020123077; 20030065292; 20030079758; 20030091641; 20030099602; 20030103912; 20030111420; 20030121868; 20030134783; 20030178044; 20040110738; 20040116371; 20040116845; 20040129112; 20040131698; 20040156883; 20040156884; 20040176312; 20040191329; 20040254545; 20050003725; 20050013836; 20050032093; 20050049181; 20050064019; 20050143286; 20050147719; 20050158263; 20050202424; 20050233950; 20050249695; 20060001865; 20060018945; 20060034782; 20060067951; 20060110456; 20060120916; 20060138058; 20060162014; 20060177384; 20060180552; 20060224103; 20060243297; 20070009566; 20070010856; 20070020309; 20070062884; 20070083156; 20070098651; 20070098674; 20070098745; 20070106232; 20070109535; 20070116750; 20070116798; 20070134649; 20070190090; 20070202770; 20070224161; 20070231406; 20070232167; 20070244059; 20070258913; 20080014247; 20080014278; 20080014286; 20080044491; 20080050452; 20080075730; 20080085282; 20080085866; 20080107707; 20080109017; 20080113001; 20080138634; 20080181923; 20080206183; 20080206305; 20080248087; 20080268189; 20080286847; 20080293607; 20080318268; 20080318269; 20090033930; 20090048324; 20090050575; 20090069406; 20090074825; 20090099533; 20090112186; 20090133810; 20090143230; 20090155215; 20090163964; 20090163965; 20090163977; 20090171263; 20090177139; 20090177254; 20090181106; 20090202516; 20090214603; 20090221704; 20090238923; 20090260632; 20090263438; 20090270475; 20090318382; 20090324574; 20100015245; 20100016767; 20100021587; 20100028396; 20100048446; 20100055086; 20100056415; 20100059433; 20100096340; 20100129297; 20100129466; 20100130450; 20100133114; 20100136072; 20100136143; 20100145412; 20100152101; 20100158966; 20100158967; 20100173366; 20100174346; 20100178268; 20100183738; 20100189706; 20100221198; 20100234792; 20100234793; 20100240017; 20100241048; 20100241049; 20100241050; 20100241051; 20100241052; 20100241053; 20100241054; 20100241055; 20100247374; 20100249692; 20100254967; 20100255178; 20100266716; 20100272768; 20100286198; 20100292629; 20100298208; 20100305062; 20100316643; 20100322903; 20110003001; 20110008402; 20110008786; 20110027252; 20110027384; 20110029076; 20110033520; 20110033882; 20110039761; 20110039762; 20110039763; 20110046041; 20110052664; 20110077192; 20110086101; 20110098323; 20110104179; 20110105376; 20110117158; 20110117160; 20110119774; 20110124716; 20110129454; 20110135621; 20110144566; 20110150819; 20110152176; 20110152750; 20110152751; 20110152752; 20110152789; 20110152790; 20110152978; 20110160643;20110160644;20110160681;20110171123;20110171189;20110172704; 20110177048; 20110177049; 20110177050; 20110177111; 20110182873; 20110182874; 20110201692; 20110207816; 20110208021; 20110208023; 20110208026; 20110217544; 20110229586; 20110236453; 20110250290; 20110256187; 20110262511; 20110266724; 20110274730; 20110275518; 20110275912; 20110280920; 20110281921; 20110294668; 20110295088; 20110295089; 20110295090; 20110301076; 20110305872; 20110305881; 20110305895; 20110305898; 20110305909; 20110306699; 20110311647; 20110319808; 20120010187; 20120010481; 20120015870; 20120020896; 20120039945; 20120040030; 20120041285; 20120041286; 20120041287; 20120045817; 20120052052; 20120058076; 20120058167; 20120058169; 20120058933; 20120077736; 20120087887; 20120088671; 20120094007; 20120107258; 20120122729; 20120128599; 20120129794; 20120134951; 20120135925; 20120136323; 20120142583; 20120149631; 20120150119; 20120152149; 20120156645; 20120157548; 20120160779; 20120171129; 20120178971; 20120189682; 20120201869; 20120209090; 20120213697; 20120219638; 20120225098; 20120238644; 20120244126; 20120252101; 20120258089; 20120258141; 20120283174; 20120288566; 20120288571; 20120294900; 20120301433; 20120308632; 20120315260; 20120321566; 20120328577;20120328671;20120328683;20120328684;20120328708;20120328713; 20120329675; 20120329746; 20130005029; 20130022578; 20130029981; 20130039978; 20130045182;20130052250;20130058983;20130059096;20130059113;20130059929; 20130071439; 20130095184; 20130101678; 20130101963; 20130102679; 20130108708; 20130110162; 20130123225; 20130123319; 20130129768; 20130129795; 20130129800; 20130131575; 20130136730; 20130136782; 20130149542; 20130150451; 20130158127; 20130158488;20130158517;20130158518;20130164228;20130164363;20130165595; 20130171210; 20130171224; 20130171228; 20130172187; 20130183435; 20130190699; 20130196365; 20130197455; 20130210708; 20130220331; 20130224258; 20130224260; 20130225675; 20130231302; 20130252818; 20130252945; 20130266522; 20130266629; 20130267471; 20130281503; 20130287860; 20130287861; 20130309219; 20130310346; 20130315874; 20130315967; 20130330386; 20130330388; 20130337088; 20130344542; 20130345261; 20140005605; 20140020138; 20140023691; 20140037688; 20140037967; 20140039195; 20140039357; 20140056951; 20140056952; 20140056993; 20140057324; 20140065200; 20140072525; 20140073560; 20140073690; 20140079741; 20140079808; 20140105986;20140107071;20140120052;20140127273;20140128313;20140142028; 20140147481; 20140155318; 20140155478; 20140161728; 20140161772; 20140161845; 20140170238; 20140171438; 20140172117; 20140186318; 20140187666; 20140193489; 20140194594; 20140205586; 20140205643; 20140212828; 20140221331; 20140221610; 20140223602; 20140228327; 20140234380; 20140241997; 20140242023; 20140243725; 20140255318; 20140257482; 20140271763; 20140271777; 20140276253; 20140276254; 20140277301;20140288007;20140288171;20140294907;20140302113;20140308217; 20140308317;20140308361;20140322351;20140322362;20140328887;20140328890; 20140328895; 20140328999; 20140335144; 20140342954; 20140348780; 20140349917; 20140350017; 20140357592; 20140370078; 20140371171; 20150005228; 20150011504; 20150018284; 20150018330; 20150024000; 20150024017; 20150024052; 20150031738; 20150038512;20150038705;20150044147;20150044260;20150045515;20150050717; 20150056411; 20150080289; 20150080290; 20150086561; 20150086631; 20150087573; 20150087582; 20150099020; 20150110898; 20150111813; 20150118219; 20150132352; 20150147775; 20150148286; 20150148612; 20150157542; 20150159180; 20150165095; 20150166706;20150166796;20150167046;20150173883;20150182667;20150183746; 20150190447; 20150197558; 20150209393; 20150224220; 20150225458; 20150225488; 20150231045; 20150231287; 20150237870; 20150238543; 20150246995; 20150259390; 20150274639; 20150283208; 20150283287; 20150297478; 20150297642; 20150299298; 20150299345;20150315253;20150322272;20150327552;20150332151;20150335013; 20150335027;20150336855;20150351383;20150351392;20150368480;20150374634; 20150374658;20150374720;20160008275;20160009733;20160010137;20160015047; 20160021882; 20160022564; 20160022595; 20160022707; 20160024551; 20160030327; 20160031941; 20160038572; 20160038650; 20160058675; 20160058693; 20160058772; 20160058816; 20160058834; 20160058998; 20160067149; 20160073638; 20160074345; 20160075749; 20160089481; 20160096865; 20160106107; 20160106689; 20160107126; 20160109401;20160120184;20160122697;20160128335;20160129078;20160135463; 20160135469;20160137563;20160137564;20160137565;20160157497;20160158169; 20160158353;20160166712;20160176815;20160184485;20160185630;20160186147; 20160193344; 20160194288; 20160198994; 20160199295; 20160206575; 20160212996; 20160213001;20160220722;20160223553;20160235698;20160235893;20160235894; 20160237145; 20160242413; 20160249612; 20160256484; 20160262384; 20160263225; 20160270411; 20160278375; 20160279191; 20160279314; 20160280772; 20160289272; 20160289287; 20160304886; 20160309711; 20160317611; 20160317618; 20160324531; 20160330962; 20160338993; 20160339071; 20160346115; 20160346161; 20160346436; 20160353739;20160355487;20160375034;20160375074;20160376449;20170007733; 20170009084; 20170014208; 20170014437; 20170020139; 20170022165; 20170022371; 20170028106; 20170029363; 20170035955; 20170042965; 20170043111; 20170044222; 20170049113;20170050893;20170050927;20170056297;20170056405;20170056437; 20170056454; 20170056455; 20170056565; 20170064966; 20170065564; 20170065673; 20170071212; 20170071986; 20170072024; 20170072098; 20170073706; 20170080130; 20170095502; 20170100328; 20170100348; 20170100512; 20170100513; 20170100514; 20170100515;20170100516;20170100517;20170100518;20170100522;20170100523; 20170106188;20170107250;20170112723;20170113038;20170119915;20170127683; 20170128338; 20170128502; 20170128720; 20170135342; 20170137380; 20170143842; 20170150724; 20170156321; 20170158727; 20170173186; 20170182205; 20170189556; 20170197028;20170202752;20170216094;20170216197;20170216369;20170216377; 20170216410; 20170224748; 20170232038; 20170232048; 20170232153; 20170240618; 20170246205; 20170246341; 20170247409; 20170247414; 20170252320; 20170258963; 20170266239; 20170266306; 20170273301; 20170274082; 20170280725; 20170281570; 20170281699; 20170283763; 20170290789; 20170290854; 20170295784; 20170296599; 20170297055; 20170312307; 20170312345; 20170326054; 20170333455; 20170333601; 20170339962; 20170340779; 20170347661; 20170347664; 20170360534; 20170360982; 20170367933;20180000993;20180008533;20180008742;20180014974;20180014975; 20180015061;20180016311;20180021463;20180028417;20180028701;20180028713; 20180030403; 20180030404; 20180030405; 20180030406; 20180036286; 20180036702; 20180037545; 20180037613; 20180042789; 20180042928; 20180043190; 20180049856; 20180051061; 20180079757; 20180079912; 20180085335; 20180085392; 20180085489; 20180085717;20180092939;20180093011;20180105792;20180110228;20180111893; 20180112068; 20180119235; 20180125066; 20180125070; and 20180133326.

Enzyme encapsulation technologies include: 4006056; 4183960; 4257884; 4310554; 4342826; 4401122; 4418148; 4431428; 4458686; 4463090; 4483921; 4622294; 4666830; 4693970; 4756844; 4783400; 4861597; 4863626; 4876039; 4898781; 4900556; 4933185; 4963368; 4965012; 5015483; 5064669; 5068198; 5089278; 5093021; 5139803; 5147641; 5167854; 5190762; 5200236; 5200334; 5225102; 5230822; 5254287; 5258132; 5262313; 5272079; 5275154; 5281355; 5281356; 5281357; 5296231; 5324436; 5352458; 5385959; 5413804; 5434069; 5437331; 5441660; 5492646; 5505713; 5506271; 5523232; 5538511; 5545519; 5589370; 5604186; 5665380; 5693513; 5698083; 5752981; 5753152; 5777078; 5788678; 5830663; 5846927; 5858117; 5858430; 5861366; 5868720; 5895757; 5929214; 6017528; 6022500; 6051541; 6127499; 6197739; 6209646; 6225372; 6242405; 6258771; 6280980; 6303290; 6313197; 6359031; 6362156; 6368619; 6369018; 6395299; 6495352; 6500463; 6541606; 6608187; 6630436; 6730212; 6730651; 6818594; 6833192; 6927201; 6943200; 6972278; 6974706; 6979669; 7008524; 7033980; 7034677; 7052913; 7060299; 7153407; 7171312; 7172682; 7195780; 7198785; 7201923; 7250095; 7267837; 7267958; 7285523; 7329388; 7351798; 7375168; 7427497; 7491699; 7553653; 7723056; 7736480; 7740821; 7750050; 7750135; 7763097; 7786086; 7811436; 7846747; 7858561; 7927629; 7939061; 7942201; 7998714; 8007724; 8007725; 8030092; 8043411; 8053554; 8066818; 8101562; 8178332; 8182746; 8226996; 8268247; 8297959; 8313757; 8318156; 8323379; 8329225; 8350004; 8354366; 8361239; 8393395; 8399230; 8404469; 8460907; 8546316; 8558048; 8568786; 8575083; 8617623; 8685171; 8709487; 8759270; 8796023; 8810417; 8834865; 8852880; 8877506; 8898069; 8927689; 8932578; 8951749; 8961544; 8974802; 8980252; 8992986; 9012378; 9024766; 9056050; 9068109; 9074195; 9084784; 9089498; 9102860; 9107419; 9109189; 9121017; 9125876; 9146234; 9187766; 9200265; 9222060; 9273305; 9321030; 9333244; 9339529; 9376479; 9393217; 9415014; 9441157; 9458448; 9464368; 9492515; 9511125; 9562251; 9580739; 9618520; 9631215; 9637729; 9687452; 9700519; 9708640; 9717688; 9738689; 9744141; 9744221; 9744247; 9765324; 9782358; 9789439; 9790254; 9895427; 9907755; 9909143; 9931302; 9931433; 9957540; 9968663; 9970000; 20010044483; 20020045582; 20020058027; 20020094367; 20020106511; 20030045441; 20030059449; 20030060378; 20030062263; 20030082238; 20030158344; 20030162284; 20030162293; 20030175239; 20030219491; 20040061841; 20040076681; 20040121926; 20040135684; 20040147427; 20040149577; 20040175429; 20040198629; 20040204915; 20040241205; 20040249082; 20040265835; 20050037374; 20050053954; 20050123529; 20050130845; 20050150762; 20050150763; 20050153934; 20050155861; 20050163714; 20050176610; 20050245418; 20050245419; 20050255543; 20060045904; 20060079454; 20060110494; 20060159671; 20060160134; 20060280799; 20070001156; 20070003607; 20070048855; 20070059779; 20070098807; 20070111329; 20070116671; 20070128714; 20070134812; 20070141096; 20070141217; 20070154466; 20070166285; 20070224273; 20070258894; 20070296099; 20080009434; 20080014622; 20080090276; 20080115945; 20080145477; 20080187487; 20080220487; 20080223722; 20080226623; 20080274092; 20080283242; 20080302669; 20080311177; 20090035381; 20090075845; 20090088329; 20090110741; 20090123553; 20090162337; 20090169677; 20090181874; 20090186077; 20090202836; 20090246318; 20090288826; 20090297592; 20090301885; 20090324476; 20100015635; 20100034799; 20100074933; 20100081849; 20100086983; 20100125046; 20100159508; 20100192986; 20100196986; 20100197548; 20100197549; 20100197550; 20100197551; 20100197552; 20100197553; 20100197554; 20100210745; 20100213062; 20100239559; 20100240116; 20100255100; 20100258116; 20100260857; 20100267594; 20100291162; 20100291828; 20100307744; 20100310612; 20100316571; 20100316620; 20110015088; 20110039164; 20110039314; 20110039751; 20110045517; 20110050431; 20110053173; 20110053283; 20110054938; 20110081394; 20110111425; 20110117623; 20110177982; 20110217363; 20110217368; 20110217553; 20110229565; 20110229580; 20110269029; 20110280853; 20110280854; 20110300201; 20110300623; 20120016217; 20120021964; 20120027848; 20120028872; 20120028873; 20120040429; 20120063276; 20120066851; 20120071379; 20120071383; 20120121570; 20120143027; 20120189703; 20120220025; 20120240961; 20120258149; 20120261256; 20120318515; 20120322713; 20130017148; 20130017610; 20130029894; 20130029895; 20130067669; 20130084312; 20130108737; 20130113129; 20130131701; 20130133102; 20130136728; 20130149357; 20130195948; 20130195985; 20130197100; 20130207042; 20130219643; 20130224172; 20130224828; 20130244301; 20130251786; 20130284637; 20130323223; 20130345099; 20140027655; 20140045241; 20140046181; 20140086988; 20140127184; 20140127305; 20140127778; 20140151042; 20140219980; 20140295520; 20140323330; 20140328801; 20140335148; 20140348815; 20150010453; 20150026840; 20150030641; 20150071894; 20150086521; 20150086599; 20150099289; 20150147308; 20150147311; 20150147365; 20150147786; 20150150955; 20150151248; 20150166975; 20150190530; 20150191607; 20150191681; 20150203799; 20150231589; 20150246104; 20150246105; 20150335589; 20150374798; 20150376594; 20160022592; 20160022598; 20160030532; 20160038608; 20160045576; 20160051484; 20160051697; 20160075976; 20160101058; 20160120956; 20160123925; 20160153025; 20160160195; 20160168559; 20160175634; 20160193307; 20160208202; 20160215242; 20160215243; 20160222068; 20160222372; 20160222437; 20160243262; 20160250304; 20160291000; 20160326215; 20160354313; 20160361361; 20170002481; 20170035891; 20170044472; 20170107461; 20170107523; 20170176453; 20170188604; 20170189501; 20170190951; 20170191005; 20170202934; 20170204316; 20170211023; 20170218315; 20170219601; 20170247493; 20170252413; 20170292063; 20170304489; 20170321160; 20170321161; 20170333360; 20170333363; 20170335244; 20170335255; 20170349818; 20170368155; 20180008549; 20180008550; 20180016569; 20180030390; 20180050115; 20180055777; 20180073046; and 20180104315.

Enzyme immobilization technologies are known. See: Barbosa, Oveimar, Rodrigo Torres, Claudia Ortiz, Ángel Berenguer-Murcia, Rafael C. Rodrigues, and Roberto Fernandez-Lafuente. “Heterofunctional supports in enzyme immobilization: from traditional immobilization protocols to opportunities in tuning enzyme properties.” Biomacromolecules 14, no. 8 (2013): 2433-2462.

Biró, Emese, Ágnes Sz Németh, Csaba Sisak, Tivadar Feczkó, and János Gyenis. “Preparation of chitosan particles suitable for enzyme immobilization.” Journal of Biochemical and Biophysical Methods 70, no. 6 (2008): 1240-1246.

Brady, Dean, and Justin Jordaan. “Advances in enzyme immobilisation.” Biotechnology letters 31, no. 11 (2009): 1639.

Cantone, Sara, Valerio Ferrario, Livia Corici, Cynthia Ebert, Diana Fattor, Patrizia Spizzo, and Lucia Gardossi. “Efficient immobilisation of industrial biocatalysts: criteria and constraints for the selection of organic polymeric carriers and immobilisation methods.” Chemical Society Reviews 42, no. 15 (2013): 6262-6276.

Datta, Sumitra, L. Rene Christena, and Yamuna Rani Sriramulu Rajaram. “Enzyme immobilization: an overview on techniques and support materials.” 3 Biotech 3, no. 1 (2013): 1-9.

Diaz, J. Felipe, and Kenneth J. Balkus Jr. “Enzyme immobilization in MCM-41 molecular sieve.” Journal of Molecular Catalysis B: Enzymatic 2, no. 2-3 (1996): 115-126.

DiCosimo, Robert, Joseph McAuliffe, Ayrookaran J. Poulose, and Gregory Bohlmann. “Industrial use of immobilized enzymes.” Chemical Soc. Reviews 42, no. 15 (2013): 6437-6474.

Fernandez-Lafuente, Roberto. “Stabilization of multimeric enzymes: Strategies to prevent subunit dissociation.” Enzyme and Microbial Technology 45, no. 6-7 (2009): 405-418.

Garcia-Galan, Cristina, Ángel Berenguer-Murcia, Roberto Fernandez-Lafuente, and Rafael C. Rodrigues. “Potential of different enzyme immobilization strategies to improve enzyme performance.” Advanced Synthesis & Catalysis 353, no. 16 (2011): 2885-2904.

Guzik, Urszula, Katarzyna Hupert- Kocurek, and Danuta Wojcieszyńska. “Immobilization as a strategy for improving enzyme properties-application to oxidoreductases.” Molecules 19, no. 7 (2014): 8995-9018.

Homaei, Ahmad Abolpour, Reyhaneh Sariri, Fabio Vianello, and Roberto Stevanato. “Enzyme immobilization: an update.” Journal of chemical biology 6, no. 4 (2013): 185-205.

Hwang, Ee Taek, and Man Bock Gu. “Enzyme stabilization by nano/microsized hybrid materials.” Engineering in Life Sciences 13, no. 1 (2013): 49-61.

Iyer, Padma V., and Laxmi Ananthanarayan. “Enzyme stability and stabilization-aqueous and non-aqueous environment.” Process biochemistry 43, no. 10 (2008): 1019-1032.

Jesionowski, Teofil, Jakub Zdarta, and Barbara Krajewska. “Enzyme immobilization by adsorption: a review.” Adsorption 20, no. 5-6 (2014): 801-821.

Juang, Ruey-Shin, Feng-Chin Wu, and Ru-Ling Tseng. “Use of chemically modified chitosan beads for sorption and enzyme immobilization.” Advances in Environmental Research 6, no. 2 (2002): 171-177.

Luckarift, Heather R., Jim C. Spain, Rajesh R. Naik, and Morley O. Stone. “Enzyme immobilization in a biomimetic silica support.” Nature biotechnology 22, no. 2 (2004): 211.

Mateo, Cesar, Jose M. Palomo, Gloria Fernandez-Lorente, Jose M. Guisan, and Roberto Fernandez-Lafuente. “Improvement of enzyme activity, stability and selectivity via immobilization techniques.” Enzyme and microbial technology40, no. 6 (2007): 1451-1463.

Parthasarathy, Ranjani V., and Charles R. Martin. “Synthesis of polymeric microcapsule arrays and their use for enzyme immobilization.” Nature 369, no. 6478 (1994): 298.

Pierre, Sébastien J., Jens C. Thies, Alex Dureault, Neil R. Cameron, Jan CM van Hest, Noëlle Carette, Thierry Michon, and Ralf Weberskirch. “Covalent enzyme immobilization onto photopolymerized highly porous monoliths.” Advanced Materials 18, no. 14 (2006): 1822-1826.

Pollak, Alfred, Hugh Blumenfeld, Michael Wax, Richard L. Baughn, and George M. Whitesides. “Enzyme immobilization by condensation copolymerization into crosslinked polyacrylamide gels.” Journal of the American Chemical Society 102, no. 20 (1980): 6324-6336.

Qhobosheane, Monde, Swadeshmukul Santra, Peng Zhang, and Weihong Tan. “Biochemically functionalized silica nanoparticles.” Analyst 126, no. 8 (2001): 1274-1278.

Rodrigues, Rafael C., Ángel Berenguer-Murcia, and Roberto Fernandez-Lafuente. “Coupling chemical modification and immobilization to improve the catalytic performance of enzymes.” Advanced Synthesis & Catalysis 353, no. 13 (2011): 2216-2238.

Rodrigues, Rafael C., Claudia Ortiz, Ángel Berenguer-Murcia, Rodrigo Torres, and Roberto Fernández-Lafuente. “Modifying enzyme activity and selectivity by immobilization.” Chemical Society Reviews 42, no. 15 (2013): 6290-6307.

Sheldon, Roger A. “Enzyme immobilization: the quest for optimum performance.” Advanced Synthesis & Catalysis 349, no. 8-9 (2007): 1289-1307.

Sheldon, Roger A., and Sander van Pelt. “Enzyme immobilisation in biocatalysis: why, what and how.” Chemical Society Reviews 42, no. 15 (2013): 6223-6235.

Spahn, Cynthia, and Shelley D. Minteer. “Enzyme immobilization in biotechnology.” Recent patents on engineering 2, no. 3 (2008): 195-200.

Taqieddin, Ehab, and Mansoor Amiji. “Enzyme immobilization in novel alginate-chitosan core-shell microcapsules.” Biomaterials 25, no. 10 (2004): 1937-1945.

Wang, Zhen-Gang, Ling-Shu Wan, Zhen-Mei Liu, Xiao-Jun Huang, and Zhi-Kang Xu. “Enzyme immobilization on electrospun polymer nanofibers: an overview.” Journal of Molecular Catalysis B: Enzymatic 56, no. 4 (2009): 189-195.

The following enzymes are known to adversely impact biofilms Proteases: Aureolysin (Aur) LapG Protease Pronase Proteinase K Savinase Spl Proteases Staphopain A (ScpA)l Staphopain B (SspB) Streptococcal Cysteine Protease (SpeB) Surface-protein-releasing enzyme (SPRE) Trypsin V8 Serine Protease (SspA) DNases DNase I DNase 1L2 Dornase alpha λ Exonuclease NucB Streptodornase Glycoside Hydrolases Alginate lyase α-amylase α-mannosidase β-mannosidase Cellulase Dispersin B Hyaluronidase PelAh PslGH Qurom-sensing signal-degrading enzymes Acylase Lactonase Combinations Glucose oxidase + lactoperoxidase Acylase I + proteinase K Cellulase + pronase

SUMMARY OF THE INVENTION

The use of exogenously provided pyruvate dehydrogenase as an adjuvant in treating biofilm-related wound infections is based an experimental finding that depleting pyruvate from the extracellular environment using this enzyme severely impairs the formation of structured Pseudomonas aeruginosa biofilms. The resulting unstructured biofilms are more susceptible to antimicrobial treatment than structured, fully mature biofilms.

See, Goodwine, James, Joel Gil, Amber Doiron, Jose Valdes, Michael Solis, Alex Higa, Stephen Davis, and Karin Sauer. “Pyruvate-depleting conditions induce biofilm dispersion and enhance the efficacy of antibiotics in killing biofilms in vitro and in vivo.” Scientific reports 9, no. 1 (2019): 3763; Goodwine, James Stephen. Enzymatic Depletion of Pyruvate using Pyruvate Dehydrogenase Induces Dispersion of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms and Poses a Potentially Powerful Anti-Biofilm Treatment Strategy for Chronic Burn Wound Infections. State University of New York at Binghamton, ProQuest Dissertations Publishing, 2018. 10928981; Han, Chendong, Enzyme-Encapsulating Polymeric Nanoparticles as a Novel Approach in Biofilm Treatments, State University of New York at Binghamton, ProQuest Dissertations Publishing, 2018. 1342216, expressly incorporated herein by reference in their entirety.

However, pyruvate dehydrogenase has limited environmental stability, and is thermally sensitive and pH sensitive. The enzyme is also costly. The use of free pyruvate dehydrogenase to deplete pyruvate in the growth medium requires treatment of the entire fluid volume, and in the case of biofilms, chronic therapy is appropriate, rather than intermittent depletion of pyruvate. Therefore, for practical applications, such as a medical therapy or industrial biofouling remediation, the use of free enzyme is a poor match. However, it has been found that pyruvate dehydrogenase may be encapsulated, for example in a permeable polymer particle, with over 10% retention of activity, resulting in an enzyme use form that can be applied locally, and has increased stability and half-life.

Nanoparticles were found to tightly adhere to biofilms, thus, enabling direct delivery of pyruvate dehydrogenase where it is needed most.

Pyruvate-depleting conditions, such as this achieved through use of immobilized or encapsulated pyruvate dehydrogenase, are used to enhance the ability of antimicrobial agents and/or the immune system to control the growth and persistence of microorganisms as surface-attached communities or biofilms. Applications arise in medical settings, aqueous systems, and where disinfection of surfaces is required. Pyruvate-depleting conditions may be used as an adjuvant to antimicrobial agents to treat microbial biofilms, such as those related to human infections and diseases, Pyruvate depletion with an antimicrobial agent may also be used to combat microbial biofilms and biofouling in aquatic systems including but not limited to cooling towers, swimming pools and spas, water distribution systems, water handling systems, industrial water systems and environmental water systems. Pyruvate-depleting conditions, with or without antimicrobial agents, can be used to prevent biofilm growth on surfaces such as indwelling medical devices, dental water units and other medical devices prone to contamination with bacteria.

Pyruvate appears to be a key regulator for biofilm formation and biofilm dispersion, with pyruvate acting as a switch to control biofilm formation, biofilm dispersion, and biofilm drug tolerance. This is supported by the findings that while biofilm formation is enhanced by the presence of pyruvate, depletion of pyruvate from the growth environment coincides with impaired biofilm formation, disaggregation of existing biofilms, and dispersed biofilms being rendered susceptible to antibiotics relative to biofilms. Pyruvate utilization appears to be a biofilm-specific adaptation of the P. aeruginosa biofilm environment to cope with reductive stress.

Pyruvate is required for both biofilm formation and maintenance of the biofilm structure, with enzymatic depletion of pyruvate coinciding with impaired biofilm formation and dispersion of established biofilms; depletion of pyruvate can achieve both prevention of biofilm formation and induction of biofilm dispersion. Pyruvate can be depleted enzymatically using pyruvate dehydrogenase (PDH).

Pyruvate dehydrogenase-treated in vitro P. aeruginosa are significantly more susceptible (>2.5 log) to tobramycin. Pyruvate dehydrogenase-treated in vivo wound biofilms are significantly more susceptible (>2.5 log) to tobramycin, as indicated using porcine burn wounds infected with a clinical P. aeruginosa isolate. Additionally, pyruvate dehydrogenase enhancing the efficacy of antibiotics is not limited to P. aeruginosa, as pyruvate dehydrogenase-treated in vitro biofilms by Staph. aureus or E. coli are significantly more susceptible to antimicrobials.

According to one embodiment, a drug delivery strategy for pyruvate dehydrogenase is provided for pyruvate management using a simple, well established drug delivery vehicle to encapsulate PDH, with encapsulation intended to enhance PDH stability while protecting the enzyme from the wound environment and the immune system.

While several molecules or dispersion cues have been reported to induce the dispersion of biofilms, with dispersed cells being more susceptible to antimicrobial agents, pyruvate-depletion inducing conditions are capable of inducing dispersion of biofilms that are insensitive to other dispersion cues or signals. This is supported by the finding that biofilms by the mutant strains bdlA, rbdA, and dipA, that are impaired in the dispersion response upon exposure to nitric oxide or nutrient cues, disperse upon induction of pyruvate-depleting conditions.

Pyruvate depletion resulting in dispersion is not being limited to the laboratory PAO1 strain OF P. aeruginosa, as pyruvate dehydrogenase (PDH) likewise induced dispersion of biofilms by clinical P. aeruginosa isolates. Moreover, consistent with dispersed cells being more susceptible to antibiotics, pyruvate-depleting conditions also render P. aeruginosa biofilms present in porcine burn wounds significantly more susceptible (5.9 log reduction) to the antibiotic tobramycin relative to treatment with tobramycin alone (2.5 log reduction). Moreover, pyruvate-depleting conditions also impair biofilm formation by Staphylococcus aureus and Escherichia coli, with depletion of pyruvate from established S. aureus and E. coli biofilms resulting in biofilm dispersion.

Thus, pyruvate-depletion may be effective when other strategies fail, and has the capacity to have an additive effect with other dispersion cues or signals.

Pyruvate-depleting conditions provide an anti-biofilm treatment strategy capable of controlling the growth and persistence of microbial biofilms. It can be combined with antimicrobial agents and the immune system, to control the growth and persistence of biofilms.

Because the utilization of pyruvate for the formation of structured biofilms appears universal, it is not limited to P. aeruginosa, and for example will apply to other pathogens and industrially important biofilm forming organisms, such as Staphylococcus aureus. Pyruvate utilization is an essential adaptation for survival during oxygen limiting conditions (such as those found in biofilms) and for the formation of high-biomass structured biofilms. Max Schobert and colleagues demonstrated that P. aeruginosa is capable of fermentatively utilizing pyruvate for survival under conditions of oxygen limitation in the absence of nitrite and nitrate (Eschbach et al., 2004, Schreiber et al., 2006). The process involves the conversion of pyruvate to lactate, acetate, and/or succinate, with the lactate and acetate-producing branches of the pathway predominating. Schobert and Jahn (Schobert & Jahn, 2010) extrapolated these findings to a model that places P. aeruginosa biofilm cells within different niches, with metabolically active cells exposed to oxygen secreting pyruvate, which then diffuses into the anoxic zones to be utilized by cells residing within these layers. Moreover, the pyruvate fermentation pathway branch converting pyruvate to lactate is required for biofilm maturation, and utilization of pyruvate for structured biofilms formation to occur both in the absence or presence of nitrate.

Research findings by the group of Dianne Newman provide further support for the importance of pyruvate utilization by P. aeruginosa. Newman’s group showed that pyruvate is released into the extracellular environment by P. aeruginosa in a manner dependent on the redox-active phenazine pyocyanin (Price-Whelan et al., 2007) and that phenazines are required for microcolony formation (Dietrich et al., 2008, Ramos et al., 2010).

Birkenstock et al (2013) recently described a Pyruvate dehydrogenase inhibitor (TPBC) that has potent antimicrobial activity against many bacterial pathogens. The use of TPBC is distinct from using exogenously provided pyruvate dehydrogenase. TPBC acts intracellularly by inhibiting pyruvate dehydrogenase, and thus a major catabolic pathway used by bacteria. This toxicity may induce distinct responses in the bacteria, development of immunity or tolerance, or other escape mechanism. Further, TPBC may be toxic or non-environmentally benign.

The pyruvate fermentation pathway branch converting pyruvate to lactate is required for biofilm maturation, and this utilization of pyruvate for the formation of structured biofilms occurs both in the absence or presence of nitrate. The required pyruvate is produced by the resident bacteria and subsequently released into the extracellular environment. The use of exogenously provided pyruvate dehydrogenase removes this pyruvate and thus, prevents biofilm maturation.

Using exogenously provided pyruvate dehydrogenase does not interfere with growth of the bacterium. Moreover, pyruvate dehydrogenase has no bactericidal activity, furthermore reducing the risk of bacteria developing resistance. However, exogenously provided pyruvate dehydrogenase depletes exogenously available pyruvate. This pyruvate is used to build structured biofilms. Depleting pyruvate impairs the formation of structured biofilms and renders biofilms more susceptible to antibiotics.

In addition to medical applications, and in particular surfaces with chronic contact with body fluids, there are also oral and dental applications.

The present technology therefore provides compositions which contain one or more enzymes that convert pyruvate to another form, preferably irreversibly under the conditions of administration or use, and necessary cofactors.

The enzyme may be administered as a therapy in a liquid, lyophilized powder, freeze dried powder, granulated powder, liposomal suspension, cream, ointment, gel, patch or film, spray coating, pill, or other pharmaceutically or dentally acceptable form. The enzyme in this case is preferably a low antigenicity form, such as mammalian or human form.

For industrial uses, the enzyme may be provided in liquid, lyophilized powder, granulated powder, liposomal suspension form, immobilized on a substrate, or other form. The enzyme in this case may be a plant, bacterial or yeast produced form.

Pyruvate dehydrogenase loses its activity at physiological temperature and high/low pH. The enzyme is active at pH 7.0-7.5. In order to prolong the activity of the enzyme, a nanoparticle can be used to encapsulate and protect it. Up to 10% of the enzyme can be encapsulated in a final formulation according to a prototype process, with encapsulated enzyme retaining bioactivity, and enzyme-loaded nanoparticles inducing biofilm dispersion in vitro.

The enzyme may be used in conjunction with a biofilm dispersion inducer, such as cis-2-decenoic acid (see, US 8,513,305, expressly incorporated by reference in its entirety), and/or an antibiotic that targets the planktonic forms of the biofilm cells. (The sessile forms may also be targeted, but typically the agents have low efficacy).

Dispersion inducers and quorum sensing factors, as discussed above, may include various factors, such as ATP, c-di-GMP, other cyclic nucleotides, cis-2-decenoic acid, Skyllamycins A to C, nitric oxide, diphenyl selenide, etc.

Various known antimicrobial treatments, as discussed above, may be employed in conjunction with the pyruvate-diminishing enzyme(s) and/or biofilm dispersing and/or disrupting treatment.

Known antibiofilm agents, which may be used in conjunction with the present technology, are discussed above.

The encapsulation process may be accompanied by various modifications of the enzyme to increase thermal and pH stability, as discussed above.

A pyruvate depleting or degrading enzyme may be provided in various forms, e.g.:

-   Antimicrobial cream -   Antimicrobial adhesive bandages or wound dressing, -   Cleaning solution for contact lenses -   Cleaning solutions in general to prevent biofouling -   Chewing gum, mouth rinse -   Aerosol/inhaler/nebulizer, for the treatment of CF lung infections -   Vesicles including outer membrane and lipid vesicles enabling     targeted delivery to site of infection -   Surface coating of indwelling devices

Typically, the enzymes for depletion of pyruvate are incompatible with certain other agents or conditions, particularly those which denature the enzymes, inhibit the enzyme, or serve to increase available pyruvate. For example, silver-based or oxidizing antimicrobial agents or agents that are protein denaturing are typically to be avoided. In some cases, the active enzyme may be protected against certain denaturing treatments, such as by encapsulation.

The enzyme may also be immobilized on an insoluble support, as discussed in detail above.

The depletion of pyruvate, such as by pyruvate dehydrogenase may be concurrently or sequentially provided with a treatment using cis-2-decenoic acid (cis-DA), or nitric oxide and compounds delivering nitric oxide. Some of these compounds are co-delivered with an antibiotic (the antibiotic serves as targeted delivery mechanisms with the design being such that when antibiotic is deactivated, nitric oxide is being released).

The enzyme is biodegradable, and generally considered non-toxic. For medical application, antigenicity is a concern.

Pyruvate management is biofilm specific. Pyruvate is an energy source (not carbon source). Pyruvate utilization by P. aeruginosa has only been linked to biofilm growth and long-term bacterial survival under oxygen limiting conditions. Moreover, pyruvate depletion by pyruvate dehydrogenase does not affect bacterial growth in liquid or susceptibility of planktonic cells. Thus, pyruvate is effective to transition the cells from sessile to planktonic state, but another therapy would normally be used to kill the cells if desired.

Long-term survival and biofilm studies have not given rise to pyruvate-insensitive mutants. Therefore, the technology may be used in chronic-type applications.

While pyruvate insensitivity has been noted upon inactivation of genes contributing to pyruvate fermentation (e.g. acnA, ldhA, mifR), these mutants were incapable of coping with the reductive stress and therefore, were unable to form biofilms.

Pyruvate dehydrogenase-induced dispersion is independent of other factors previously described to contribute to dispersion by P. aeruginosa biofilms. For instance, while biofilms by mutant strains bdlA, dipA and rbdA are impaired in their dispersion response upon sensing the dispersion cue nitric oxide, biofilms by the respective strains dispersed upon treatment with pyruvate dehydrogenase. This means that pyruvate dehydrogenase treatment should be capable of enhancing dispersion induced by other compounds such as cis-2-decenoic acid or nitric oxide releasing compounds.

Pyruvate depletion via pyruvate dehydrogenase requires pyruvate dehydrogenase to remain active. Activity is affected by environmental conditions such as pH and proteases. Therefore, the technology may be provided with pH buffers, stabilizers, antioxidants, an excess of cofactors, and in some cases, binding factors for expected inhibitors.

The pyruvate dehydrogenase enzyme shows potential for preventing bacterial infection, thus making the composition suitable for coatings to medical devices that are at risk for infection, such as heart valves, orthopedic implants, catheters, and dental implants.

Testing shows that pyruvate dehydrogenase can prevent formation of biofilms, and therefore the technology may be used preemptively, before the biofilm forms. This technology would therefore make infections much easier to treat and may be able to prevent infections if used preemptively because pyruvate depletion prevents the formation of biofilms. Furthermore, in contrast to conventional antibiotics, it is very unlikely that bacteria could become resistant to the removal of pyruvate as an energy source.

For medical use, human pyruvate dehydrogenase is preferred. Pyruvate dehydrogenase can be cloned into a vector (starting out from cDNA) and then mass produced in a bacterial or eukaryotic expression system.

Encapsulation of the enzyme, especially in a shell-core particle, can isolate the enzyme from the immune system, and thereby reduce antigenicity. Further, incorporating poly(ethylene glycol) into the polymer particle can help to combat the immune response.

The composition may be provided in gels, polymers, pastes, edible products, and chewable products.

The stabilized pyruvate diminishing enzyme may be coadministered with an additive component selected from one or more of the group consisting of biocides, surfactants, antibiotics, antiseptics, detergents, chelating agents, and/or virulence factor inhibitors.

Another aspect of the present technology relates to a method of treating or preventing a condition mediated by a biofilm in a subject. This method involves providing a subject having, or susceptible to, a condition mediated by a biofilm produced by a microorganism, whereby the biofilm comprises a matrix and the micro-organism on a surface. A stabilized pyruvate diminishing enzyme or treatment, such as encapsulated pyruvate dehydrogenase, is administered to the subject under conditions effective for to selectively act on the microorganism and have a suitable biological response without a required direct effect on the matrix, whereby the condition mediated by a biofilm in the subject is treated or prevented. Of course, direct matrix-active treatments may be provided in conjunction.

According to one embodiment, the enzyme is immobilized to biofilm matrix components or to sterile particles of formed biofilm matrix.

A further embodiment is directed to a method of treating or inhibiting formation of a biofilm on a surface. This involves providing a surface having or being susceptible to formation of a biofilm produced by a microorganism, whereby the biofilm comprises a matrix and the micro-organism on the surface. A stabilized pyruvate diminishing agent is deployed at the surface under conditions effective reduce pyruvate concentration in the medium surrounding the microorganism and have a suitable biological response, whereby formation of the biofilm on the surface is prevented, or treated.

One way to reduce the concentration of pyruvate in a medium, especially when produced in small quantities by the biofilm itself, is by absorption of pyruvate to an affinity material, such as a molecularly imprinted polymer sheet. While such materials typically do not chemically alter the pyruvate, the same material may include enzymes, catalysts, reagents, reactants, etc., that act on the relatively higher concentrations of pyruvate absorbed in the material to alter or degrade it. The imprinting may be guided by the active site of enzymes or pyruvate transporters, which have a high affinity for pyruvate; for example. All or portions of the enzymes or transports themselves may be included in the imprinting. Since retention of catalytic or transport activity, or other biologic function is not necessarily required for the affinity to be maintained, the preparation, storage, or use may include or be subject to relatively harsher conditions than would be required for retention of specific biological activity. See:

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Luo, Jing, Sisi Jiang, and Xiaoya Liu. “Efficient one-pot synthesis of mussel-inspired molecularly imprinted polymer coated graphene for protein-specific recognition and fast separation.” The Journal of Physical Chemistry C 117, no. 36 (2013): 18448-18456.

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The examples of situations in which disruption of biofilm formation or maintenance would be of benefit include improved cleaning of contact lenses and teeth, improved antiseptic activity in the home, in industry, and in the medical community and enhanced cidal activity for existing antibiotic treatments such as with burn patients infected with Pseudomonas aeruginosa.

The method may further include administering to the biofilm, an antimicrobial treatment. The treatment can be the administration of biocides, surfactants, antibiotics, antiseptics, detergents, chelating agents, virulence factor inhibitors, gels, polymers, pastes, edible products, chewable products, ultrasonic treatment, radiation treatment, thermal treatment, and/or mechanical treatment.

In one embodiment, the surface to be treated includes indwelling medical devices, such as catheters, respirators, and ventilators. In addition, the surface can be in implanted medical devices, including stents, artificial valves, joints, pins, bone implants, sutures, staples, pacemakers, and other temporary or permanent devices. The pyruvate diminishing treatment, e.g., enzyme, can also be included in surgical glue, or in a coating on the medical device.

In another embodiment, the surface to be treated includes drains, tubs, kitchen appliances, countertops, shower curtains, grout, toilets, industrial food and beverage production facilities, flooring, and food processing equipment.

In a further embodiment, the surface to be treated is a heat exchanger surface or a filter surface. Thus, treatment provides a means for reducing the degree of biofouling of the heat exchanger or filter.

In another embodiment, the surface to be treated is a marine structure which includes boats, piers, oil platforms, water intake ports, sieves, and viewing ports.

The surface can alternatively be associated with a system for water treatment and/or distribution (e.g., a system for drinking water treatment and/or distributing, a system for pool and spa water treatment, a system for treatment and/or distribution of water in manufacturing operations, and a system for dental water treatment and/or distribution).

The surface can also be associated with a system for petroleum drilling, storage, separation, refining and/or distribution (e.g., a petroleum separation train, a petroleum container, petroleum distributing pipes, and petroleum drilling equipment).

The treatment can also be included in formulations directed at reducing or eliminating biofilm deposits or biofouling in porous medium, such as with oil and gas bearing geological formations. The treatment may be accomplished by applying a coating, such as paint, to the surface.

The treatment may include, in addition to a pyruvate diminishing component, e.g., pyruvate dehydrogenase, a dispersion inducer and/or a biocide. Enzymatic components may be encapsulated and/or immobilized, to improve thermal and chemical stability, maintain localization, and reduce antigenicity, for example. The antibiotic or biocide, and dispersion inducer, mat be provided in a controlled or extended release formulation. In some cases, the same particles that encapsulate or immobilize the enzyme, may also serve as extended release reservoirs for a biocide and/or a dispersion inducer.

The method of inhibiting formation of a biofilm on a surface may further involve administering to the surface, an antimicrobial treatment. The treatment can be administration of biocides, surfactants, antibiotics, antiseptics, disinfectants, medicines, detergents, chelating agents, virulence factor inhibitors, ultrasonic treatment, radiation treatment, thermal treatment, and mechanical treatment.

The pyruvate diminishing component can be coated on, or impregnated in, a surface in order to inhibit formation of a biofilm on the surface. The pyruvate diminishing component can also be in a copolymer or a gel coating over the surface.

The present technology also relates to a method of treating subjects with burns. The method involves administering the pyruvate diminishing component under conditions effective to treat burns in the subject. A specific application provides a topical dressing for burn patients comprising an encapsulated or immobilized mammalian or human pyruvate dehydrogenase, in micron or nanoparticle form, as a powder, cream, ointment, dressing, or flowing medium over the wound. In some cases, the fluid is transported to an immobilized enzyme filter, which reduces the pyruvate concentration to a very low level, e.g., <0.1 mM, and the fluid may be recirculated back to the wound. The fluid may be unfused with an antibiotic and/or dispersion inducer. The fluid drawn from the would may be filtered, such as through a 0.2 µm filter, to remove bacteria, or treated with an antibacterial process, such as ultraviolet light. However, the recycling of at least a portion of the same fluid back to the would be advantageous because it contains various growth factors, which assist in would healing, which would otherwise be lost in the case of mere flushing of the wound.

The present technology further relates to a method of treating and/or preventing dental plaque, dental carries, gingival disease, periodontal disease, and oral infection in a subject by providing a pyruvate diminishing component which acts to reduce pyruvate in the oral cavity. The method involves treating the oral cavity of the subject with the pyruvate diminishing component, such as pyruvate dehydrogenase in a composition that deposits stabilized (e.g., immobilized or encapsulated) enzyme on tooth surfaces, and other oral tissues. Treating can be carried out with a dentifrice, mouthwash, dental floss, gum, strip, toothpaste, a toothbrush, and other preparations, containing the stabilized pyruvate dehydrogenase. The composition may also contain other compounds known in the dental arts that are typically added to dental compositions. For example, the composition may also include fluoride, desensitizing agents, anti-tartar agents, anti-bacterial agents, remineralization agents, whitening agents, and anti-caries agents.

The amount of pyruvate diminishing component (and any necessary cofactors) is preferably sufficient to reduce the medium concentration by at least 90%, and preferably at least 95%, for example to less than 1 mM, and preferably less than 0.1 mM, and more preferably less than 0.05 mM, over the course of less than 30 minutes at 37° C.

The present technology may also be used for cleaning and/or disinfecting contact lenses. The method involves treating contact lenses with a cleaning and/or disinfecting solution containing a pyruvate diminishing component. The contact lens may be treated in this manner while being stored in solution or while being used in vivo. Alternatively, the pyruvate diminishing component can be used in eye drops. According to one embodiment, the contact lenses are disposable, and the pyruvate dehydrogenase or other enzyme is immobilized on or in the lens itself.

The present technology further relates to a method of treating and/or preventing acne or other biofilm-associated skin infections on the skin of a subject. The method involves treating the skin of the subject with the pyruvate diminishing component according to the present technology under conditions effective to treat and/or prevent the acne or biofilm-associated skin infections. The pyruvate diminishing component may be present in an ointment, cream, liniment, salves, shaving lotion, or aftershave. It may also be present in a powder, cosmetic, ointment, cream, liquid, soap, gel, cosmetic applicator, and/or solid, woven or non-woven material intended to contact or be proximate with the skin.

The present technology also relates to a method of treating and/or preventing a chronic biofilm-associated disease in a living subject. The method involves administering to the subject a pyruvate diminishing component under conditions effective to treat and/or prevent the chronic biofilm-associated disease. The chronic biofilm-associated diseases to be treated and/or prevented include, but are not limited to, middle ear infections, osteomyelitis, prostatitis, colitis, vaginitis, urethritis, sinovial infections, infections along tissue fascia, respiratory tract infections (e.g., infections associated with lung infections of cystic fibrosis patients, pneumonia, pleurisy, pericardial infections), genito-urinary infections, and gastric or duodenal ulcer infections. For gastric or duodenal ulcers caused by Helicobacter pylori, the pyruvate diminishing component will need to function at a pH of below 5.5. The pyruvate diminishing component, e.g., immobilized enzyme, may be administered in combination with an antimicrobial agent, such as biocides, surfactants, antibiotics, antiseptics, detergents, chelating agents, or virulence factor inhibitors. In the case of gastric therapies, acid reducing therapies, such as antacids, proton pump inhibitors, antihistamines, and the like may also be employed.

Note that systemic administration of pyruvate dehydrogenase to reduce pyruvate levels of plasma is likely infeasible, and possibly toxic. Therefore, the therapy is preferably applied extracorporeally, in or on medical devices, or in body compartments other than the vasculature.

The present technology may provide compositions and methods in which the encapsulated, immobilized, or otherwise stabilized enzyme is provided in a personal care product, such as eye drops, eyewash solution, contact lens care solution, contact lens cleaning solution, contact lens storing solution, contact lens disinfectant, contact lens cleaning-storing solution, and contact lens cleaning disinfecting-storing solution, contact lens containers, contact lenses, as well as podiatric, manicure and pedicure solutions, gels, creams, jellies, powders, pastes, lotions, soaps and cleaners.

A further aspect of the present technology is directed to a composition comprising: a component selected from one or more of the group consisting of biocides, surfactants, antibiotics, antiseptics, detergents, chelating agents, virulence factor inhibitors, gels, polymers, pastes, edible products, and chewable products. For example, pyruvate dehydrogenase may be provided in a chewing gum or gel, which is active when chewed to reduce oral pyruvate levels over the course of a duration of at least 30 minutes.

The composition, in the case of a contact lens cleaning product, may comprise one or more ingredients selected from the group consisting of: water, citrate buffer, citric acid, stabilizing agent, a flavoring agent, vitamins, minerals, herbals, a surfactant, an antimicrobial peptide, an antimicrobial and a pH adjuster. The antimicrobial preservatives can be selected from potassium sorbate, potassium benzoate, sodium benzoate and benzoic acid, and can, in particular be used in contact lens cleaning and disinfecting solutions. The antimicrobial preservative can be in a concentration ranging from 0.25 g/L to 3 g/L.

The technology may further provide methods of preparing suitable formulations for treating or impregnating personal care products, including contact lenses, contact lens containers, and manicure, pedicure and podiatry tools and containers.

The technology may also provide methods of preparing a suitable formulation for use with the personal care products in a variety of ways, for example in a disinfecting solution, a lotion, cream, a gel, a spray, a thermoreversible gel spray, and a paste.

The formulations can also include natural or synthetic flavorings and coloring agents. Thickening agents can also be added to compositions of the invention such as guar gum, carbopol, polyethylene glycol, pluronic F-127, sodium alginate, carboxymethyl cellulose, xanthan gum and other personal care acceptable thickening agents.

Other formulations will be readily apparent to one skilled in the art. A composition of the invention can include antibiofilm enzymes (cellulase, beta-N-acetylgluconase, DispersinB, papain, DNase 1, etc.), antimicrobial peptides, antibiotics (gentamicin, ciprofloxacin, ampicillin, cefamendole nafate, rifambicin, etc.), antimicrobials (triclosan, chlorhexidine, quaternary ammonium compounds, silver, silver salts, etc.) and other antibiofilm compounds.

The technology may also provide liposomal or nanoparticle delivery systems that enhance the stability and efficacy of compounds in the compositions.

The technology also provides personal care products treated, coated, or impregnated with a composition of the invention, such as a contact lens, a contact lens container, a hand washing container, a hand or foot scrubber, and a foot washing container.

In an embodiment, a composition comprises an antibiotic, optionally with chelating agents and a metal ion salt. Groups of antibiotics useful in conjunction with the technology include, but are not limited to, β-lactam inhibitors (e.g., penicillin, ampicillin, amoxicillin, methicillin, etc.), cephalosporins (e.g., cephalothin, cephamycin, etc.), aminoglycosides (e.g., streptomycin, tobramycin, etc.), polyenes (e.g., amphotericin, nystatin, etc.), macrolides (e.g., erythromycin, etc.), tetracyclines (e.g., tetracycline, doxycycline, etc.), nitroimidazole (e.g., metronidazole), quinolones (e.g., nalidixic acid), rifamycins (e.g., rifampin), and sulfonamides (e.g., sulfanilamide), nitroaromatics (e.g., chloramphenicol) and pyridines (e.g., isoniazid).

In an embodiment, a composition comprises an antiseptic, a pyruvate depleting enzyme and associated cofactors. Antiseptics are agents that kill or inhibit the growth of microorganisms on the external surfaces of the body. Antiseptics include, but are not limited to, triclosan, chlorhexidine salt, and cetylpyridinium chloride.

Antibiofilm compounds include, but not limited to, DispersinB, DNase I, Proteinase K, apyrase, cis-2-decenoic acid, nitric oxide, alginate lyase, lactoferrin, gallium, cellulase, and 5-fluorouracil.

In general, methods of manufacturing anti-infective compositions may comprise combining a personal care or pharmaceutically acceptable carrier and an effective amount of a pyruvate depleting composition, and optionally other agents, such as a biofilm dispersion inducer, chelating agents and a metal ion salt with an antiseptic, an antibiotic, a bacteriocin, an antimicrobial peptide or chitosan.

It is therefore an object to provide a composition, comprising purified pyruvate dehydrogenase, encapsulated in a polymeric nanoparticle, and being stable when hydrated at up to 37° C. for at least 48 hrs.

It is also an object to provide a method of modifying a biofilm, comprising administering a stabilized form of pyruvate dehydrogenase, which retains at least 50% of its initial activity after 48 hrs at 37° C., and required cofactors, in a sufficient quantity to reduce a pyruvate level in an aqueous medium surrounding the biofilm, to cause a biological response of hypoxic cells within the biofilm to the reduction in pyruvate.

It is a further object to provide a method of treating or preventing a biofilm, comprising: providing a subject having, or susceptible to, a condition mediated by a biofilm produced by a microorganism, whereby the biofilm comprises a matrix and the microorganism on a surface; and administering to the subject a nanoparticle formulation having pyruvate dehydrogenase activity, under conditions effective for the condition caused by a biofilm in the subject to be treated or prevented.

It is also an object to provide a method of treating or inhibiting formation of a biofilm on a surface, comprising: providing a surface having or being susceptible to formation of a biofilm produced by a microorganism, whereby the biofilm comprises a matrix and the microorganism on the surface; and administering to the surface a pyruvate degrading enzyme under conditions effective reducing formation or maintenance of the biofilm on the surface to be treated or inhibited.

A composition, comprising purified enzyme, within a particle, effective for reducing pyruvate concentration in an aqueous suspension of the composition.

The composition may be provided in combination with CoA and NADH or an enzyme cofactor redox agent. The enzyme in hydrated form, is preferably stable for at least 48 hrs at 37° C., and e.g., maintain at least 50% of its initial activity after 48 hrs at 37° C.

The particle may comprise a liposome, or a nanoparticle. The particle may have a mean diameter of less than 1 micron. The particle may comprise a polymeric matrix, polymeric nanoparticle, a carbohydrate matrix, poly(lactic-co-glycolic acid), or chitosan. The enzyme may comprise pyruvate dehydrogenase, lactate dehydrogenase, formate dehydrogenase, or a transaminase. The particle may selectively bind to biofilms. The enzyme may be immobilized to a particle matrix, or encapsulated within a particle matrix, or within a liposome or vesicle. The particle may comprise an ionic exchange resin or matrix or other material, with an affinity for pyruvic acid. The composition may be provided in combination with a bacterial biofilm dispersion inducer, e.g., cis-2-decenoic acid, nitric oxide, and/or an antibiotic. The particle may further comprise cis-2-decenoic acid. The antibiotic may be an aminoglycoside, tobramycin, gentamicin, amikacin, a quinolone, ciprofloxacin, levofloxacin, a cephalosporin, ceftazidime, cefepime, cefoperazone, cefpirome, ceftobiprole, an antipseudomonal penicillin selected from the group consisting of a: carboxypenicillin, carbenicillin, ticarcillin, a ureidopenicillin, mezlocillin, azlocillin, and piperacillin, a carbapenem, meropenem, imipenem, doripenem, polymyxin B, colistin, colicin, a bacteriocin, a microcin, a monobactam, or aztreonam.

It is a further object to provide a method of inducing a dispersion of sessile organisms of a biofilm in an aqueous medium, comprising depleting pyruvate in the aqueous medium to a sufficient amount to induce a dispersion response of the sessile organisms. The depletion of pyruvate in the aqueous medium is preferably sufficient to alter response of cells in the biofilm to hypoxic stress. The depletion may comprise enzymatically altering the pyruvate to another chemical species. The enzymatic alteration may be reversible or irreversible, e.g., a decarboxylation, or a phosphorylation. The depletion may comprise absorbing pyruvate to an insoluble resin or other matrix or material, chemically transforming the pyruvate to another chemical species, decarboxylation reaction, an electrochemical reaction, an imine-forming reaction, absorption of pyruvate in a molecular sieve, absorption of pyruvate in a weakly basic anion exchange resin, operation of a transaminase in presence of pyridoxal phosphate, operation of pyruvate decarboxylase, use of a bioreactor comprising pyruvate fermentative organisms, transport of pyruvate across a lipid bilayer membrane with a pyruvate carrier. The dispersion response may be secondary to a hypoxic response of cells in the biofilm. The pyruvate may be produced, at least in part, by cells at the periphery of the biofilm.

It is another object to provide a method of modifying a biofilm, reducing a pyruvate level in an aqueous medium surrounding the biofilm, to cause a biological response of hypoxic cells within the biofilm to the reduction in pyruvate. The reduction may comprise administering an enzyme preparation. The enzyme preferably retains at least 50% of its initial activity after 48 hrs at 37° C. The enzyme may comprise purified pyruvate dehydrogenase, purified pyruvate oxidase, purified lactate dehydrogenase, a purified transaminase, e.g., alanine transaminase. The reduction may comprise absorbing the pyruvate, decarboxylating the pyruvate, aminating the pyruvate, amidating the pyruvate, phosphorylating the pyruvate, adsorbing the pyruvate, reacting the pyruvate with an immobilized enzyme, reacting the pyruvate with an encapsulated enzyme. The method may further comprise administering a bacterial biofilm dispersion inducer, or administering an antibiotic.

It is a further object to provide a method of treating a biofilm, comprising administering to a subject having a biofilm-associated infection, a nanoparticle formulation comprising an enzyme having a pyruvate substrate specificity, under conditions effective for the condition caused by a biofilm in the subject to be treated by a response of the biofilm to a reduction in environmental pyruvate. The method may further comprise administering a bacterial biofilm dispersion inducer to the subject, or administering to the subject an antimicrobial treatment selected from the group consisting of one or more of biocides, surfactants, antibiotics, antiseptics, detergents, chelating agents, and virulence factor inhibitors. The biofilm-associated infection is caused by a burn, caused by at least one of dental plaque, dental caries, gingival disease, and an oral infection, caused by at least one of dental plaque, dental caries, gingival disease, and an oral infection, associated with acne, or associated with a chronic biofilm infection. The administering may be carried out with a dentifrice, mouthwash, dental floss, gum, strip, brush, bandage, irrigator, bioerodable polymer, hypodermic needle, a lotion, cream, ointment, or gel.

Another object provides a method of treating a biofilm on a surface, comprising: providing a surface having a biofilm; and administering to the surface a treatment that reduces a concentration of pyruvate of the biofilm, comprising pyruvate produced by at least a portion the biofilm, under conditions effective reducing maintenance of the biofilm on the surface.

The treatment may comprise a pyruvate degrading enzyme, e.g., pyruvate dehydrogenase, pyruvate decarboxylase, or lactate dehydrogenase. The enzyme may be encapsulated. The surface may be part of a contact lens, an indwelling medical device selected from the group consisting of a catheter, a respirator, and a ventilator, an implanted medical device selected from the group consisting of a stent, an artificial valve, a joint, a suture, a staple, a pacemaker, a bone implant, and a pin, a drain, a tubs, a kitchen appliance, a countertop, a shower curtain, grout, a toilet, an industrial food and beverage production facility, a floor, and a piece of food processing equipment, a heat exchanger surface or a filter surface, a marine structure selected from the group consisting of a boat, a pier, an oil platform, a water intake port, a sieve, and a viewing port, or a water treatment system or a water distribution system. The water treatment system or a water distribution system is selected from the group consisting of a system for drinking water treatment and/or distribution, a system for pool and spa water treatment, a system for treatment and/or distribution of water in manufacturing operations, and a system for dental water treatment and/or distribution. The method may comprise coadministering to the surface, in conjunction with said administering the treatment, at least one antimicrobial treatment selected from the group consisting of biocides, surfactants, antibiotics, antiseptics, detergents, chelating agents, virulence factor inhibitors, ultrasonic treatment, radiation treatment, thermal treatment, and a mechanical treatment. The treatment and the antimicrobial treatment may be administered simultaneously. The method may further comprise coadministering to the surface, in conjunction with said administering the treatment, at least one physiological dispersion inducer. The treatment and the physiological dispersion inducer may be administered simultaneously. The treatment may comprise an enzyme administered in a copolymer or a gel coating over the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows that depletion of pyruvate from the growth medium via pyruvate dehydrogenase (PDH) impairs biofilm formation.

FIGS. 2A-2H show that pyruvate depletion induces biofilm dispersion within 24 h of exposure to PDH or heat-inactivated (HK) PDH, as indicated by (2A) crystal violet (CV) staining of the attached biofilm biomass, (2B) increased turbidity and (2C) number of viable cells in the supernatant. (2D) CV stained biofilms obtained in the absence (top wells) and presence (bottom wells) of PDH. (2E) Confocal images of biofilms in the absence (2E1)/presence of active (2E3) or heat-inactivated (2E2) PDH. (2F1, 2F2) intact and dispersed biofilm microcolony. (2G, 2H) Dispersion proportion and microcolony diameter in absence, and presence of active or heat-inactivated PDH. Error bars represent standard deviation.

FIGS. 3A and 3B show that pyruvate depletion-induced dispersion is dependent on the diameter of microcolonies. Microcolony diameter of (3A) dispersed and (3B) non-dispersed biofilm microcolonies following exposure to PDH. Untreated biofilms were used as control. On average, 100 microcolonies per biofilm were evaluated.

FIG. 4A-4D4 show that excess pyruvate or inactivation of genes involved in pyruvate fermentation processes abrogate the dispersion response. (4A) Remaining PAO1 biofilm biomass post PDH treatment in the absence/presence of excess lactate and pyruvate. Inactivation of (4B) ldhA or (4C) mifR encoding lactate dehydrogenase and microcolony formation regulator MifR, respectively, renders mutant biofilms insensitive to pyruvate depletion. Error bars represent standard deviation. (4D) Confocal images of untreated (4D1, 4D3) or PDH-treated biofilms by ΔmifR (4D2) and ΔmifR/pJN-mifR (4D4).

FIGS. 5A and 5B show that PDH treatment increases the efficacy of tobramycin in killing PAO1 biofilms. (5A) Number of viable biofilm cells remaining post treatment. (5B) Log reduction. Biofilms were treated with tobramycin (Tob, 150 µg/mL). Error bars represent standard deviation.

FIG. 6 shows that PDH treatment induces dispersion of biofilms by clinical isolate. P aeruginosa clinical isolates were isolated from indicated sites. Error bars represent standard deviation.

FIGS. 7A-7C show CV staining (see 7A inset) of microcolonies, showing (7A) biofilm biomass after treatment with LB media, control, 5, 10 and 20 mU/ml PDH. (7B) brightfield microscopy. (7C) biofim biomass for control, 5 and 10 mU/ml.

FIGS. 8A-8B show CV staining biomass for (8A) PDH and cofactors, and (8B) exogenous pyruvate.

FIGS. 9A and 9B show CV staining, (9A) biomass and (9B) brightfield microscopy, of PAO1 and mutants for control and PDH.

FIGS. 10A and 10B show control and PDH of (10A) confocal fluorescence microscopy and (10B) biofilm biomass for PA14 and mutants.

FIG. 11 shows CV staining biofilm biomass for PAO1, PA14, CF lung, chronic wound, and using P aeruginosa clinical isolates with and without PDH.

FIGS. 12A-12C show the effect of (12A) tobramycin alone, or with PDH, (12B, 12C) tobramycin, tobramycin with PDH or PDH on log reduction of biofilm CFU.

FIG. 13 shows the effect of nitrate on CV staining biofilm mass, for control and PDH treated microcolonies.

FIGS. 14A and 14B show the in vivo relevance of the technology.

FIGS. 15A-15F show the effect of PDH nanoparticles (NP) on biofilms.

FIG. 16 shows that nitric oxide can enhance pyruvate dehydrogenase-induced dispersion in biofilms.

FIGS. 17A and 17B shows reduction in biofilm burden in wounds by reduction in colony forming units (CFU) (17A) and log₁₀ reduction (17B) by use of pyruvate dehydrogenase (PDH) alone, silver sulfadiazine (SSD) cream alone, and PDH and SSD together.

FIG. 18 shows biochemical pathways of pyruvate.

FIG. 19 shows the pyruvate decarboxylase mechanism.

FIG. 20 shows the ylide resonance form of thiamine pyrophosphate (TPP).

DETAILED DESCRIPTION

A hallmark of biofilms is their extreme tolerance to antimicrobial agents, rendering infections by biofilms to conventional treatment therapies. This has brought on the realization that successful treatment of biofilm infections will require the development of novel treatment strategies. It is thus not surprising that biofilm dispersion, a regulatory response to environmental cues, allowing bacterial cells to convert to the planktonic state, has become a major focus of recent research endeavors to combat biofilms. However, while much attention has been paid to agents inducing biofilm dispersion, little is known about the mechanism underlying dispersion.

Depletion of Pyruvate Coincides With Reduced Biofilm Biomass

P. aeruginosa has been demonstrated to require autogenously produced pyruvate and pyruvate fermentative processes as a means of redox balancing to form microcolonies, with depletion of pyruvate or inactivation of components of the pyruvate fermentation pathway impairing biofilm formation. Considering that transition to the free-living state is initiated within microcolonies as indicated by microcolonies having central voids, pyruvate availability was hypothesized to play a role in dispersion. Enzymatic depletion of pyruvate from the growth medium of established P. aeruginosa biofilms coincided with a significant decrease in biofilm biomass, and central hollowing of microcolonies indicative of dispersion.

No dispersion was noted by strains inactivated in components of the pyruvate fermentation pathway, in the presence of excess pyruvate or heat-inactivated enzyme. Moreover, pyruvate depletion-induced dispersion coincided with enhanced killing of biofilm cells by the aminoglycoside tobramycin.

Pyruvate plays an essential role in the formation of biofilms, as continuous depletion of pyruvate (via pyruvate dehydrogenase plus cofactors) from the growth medium prevented biofilm formation. Given the role of pyruvate in establishing biofilms characterized by a three-dimensional architecture, the requirement for pyruvate by biofilms to remain surface-attached and maintain their three-dimensional architecture was investigated.

FIG. 1 shows that depletion of pyruvate from the growth medium via pyruvate dehydrogenase (PDH) impairs biofilm formation.

FIGS. 2A-2H show that pyruvate depletion induces biofilm dispersion within 24 h of exposure to PDH or heat-inactivated (HK) PDH, as indicated by (2A) crystal violet (CV) staining of the attached biofilm biomass, (2B) increased turbidity and (2C) number of viable cells in the supernatant. (2D) CV stained biofilms obtained in the absence (top wells) and presence (bottom wells) of PDH. (2E) Confocal images of biofilms in the absence (2E1)/presence of active (2E3) or heat-inactivated (2E2) PDH. (2F1, 2F2) intact and dispersed biofilm microcolony. (2G, 2H) Dispersion proportion and microcolony diameter in absence, and presence of active or heat-inactivated PDH. Error bars represent standard deviation.

FIGS. 3A and 3B show that pyruvate depletion-induced dispersion is dependent on the diameter of microcolonies. Microcolony diameter of (3A) dispersed and (3B) non-dispersed biofilm microcolonies following exposure to PDH. Untreated biofilms were used as control. On average, 100 microcolonies per biofilm were evaluated.

FIG. 4A-4D4 show that excess pyruvate or inactivation of genes involved in pyruvate fermentation processes abrogate the dispersion response. (4A) Remaining PAO1 biofilm biomass post PDH treatment in the absence/presence of excess lactate and pyruvate. Inactivation of (4B) ldhA or (4C) mifR encoding lactate dehydrogenase and microcolony formation regulator MifR, respectively, renders mutant biofilms insensitive to pyruvate depletion. Error bars represent standard deviation. (4D) Confocal images of untreated (4D1, 4D3) or PDH-treated biofilms by ΔmifR (4D2) and ΔmifR/pJN-mifR (4D4).

FIGS. 5A and 5B show that PDH treatment increases the efficacy of tobramycin in killing PAO1 biofilms. (5A) Number of viable biofilm cells remaining post treatment. (5B) Log reduction. Biofilms were treated with tobramycin (Tob, 150 µg/mL). Error bars represent standard deviation.

FIG. 6 shows that PDH treatment induces dispersion of biofilms by clinical isolate. P aeruginosa clinical isolates were isolated from indicated sites. Error bars represent standard deviation.

P. aeruginosa biofilms grown for 4 days in 24-well plates were exposed to pyruvate-depleting conditions. This was accomplished by exposing biofilms to increasing concentration of the enzyme pyruvate dehydrogenase (PDH) having a specific activity of 0.57 U/mg. PDH catalyzes the conversion of pyruvate to acetyl-CoA in the presence of CoA and NAD⁺. Specifically, biofilms were exposed to 5, 10, and 20 mU (8.7, 17.4, and 32.8 mg enzyme) of PDH in the presence of NAD⁺ and CoA. Biofilms grown in LB but left untreated were used as controls. Following overnight incubation, the remaining biofilm was stained using crystal violet. Relative to untreated biofilms, PDH treatment coincided with a significant loss in the CV-stainable biofilm biomass, with exposure to 5 mU resulting in a 2.2-fold reduction in the biofilm biomass while exposure to 10 and 20 mU resulted on average in a 2.9-fold reduction (FIG. 7A).

To determine whether biofilms of different age are susceptible to pyruvate depleting conditions, biofilms grown for 2, 5, and 6 days were exposed to pyruvate depleting conditions, by treating biofilms with 10 mU PDH in the presence of cofactors. Following incubation for 16 hr, microscopic evaluation of the remaining biofilms indicated exposure of biofilms to PDH and thus, pyruvate depleting conditions, to coincide with a significant reduction in the biofilm biomass relative to the biofilms that were left untreated (FIG. 7B).

These findings suggested exposure to PDH contributes to the loss of biofilm biomass regardless of the biofilm age, likely by inducing pyruvate-depleting conditions. This was further supported by the finding that exposure of biofilms to increasing concentrations of heat-inactivated PDH had no effect on the biofilm biomass relative to untreated biofilms (FIG. 7C).

Pyruvate-Depletion Induced Dispersion is Inhibited by Pyruvate But Not by Acetyl-CoA or Lactate

The effect of cofactors on the biofilm biomass was determined to ensure that PDH affects the biofilm biomass by inducing pyruvate-depleting conditions. PDH requires NAD⁺ and CoA as cofactors to enzymatically convert pyruvate to acetyl-CoA and NADH. Exposure of biofilms to NAD⁺ and CoA or NAD+ alone had no effect on the biofilm biomass accumulation (FIG. 8A). In addition, to determine whether exposure to PDH is due to pyruvate depletion or the accumulation of the end products of the PDH catalyzed reaction, acetyl-CoA and NADH, biofilms were exposed to 0.2 mM acetyl-CoA or 2 mM NADH. Analysis of the biofilm biomass relative to untreated biofilms indicated that exposure of biofilms to acetyl-CoA or NADH did not result in increased biofilm biomass accumulation (FIG. 8A). As in P. aeruginosa, pyruvate dehydrogenase contributes to the formation of lactate, the effect of lactate on the biofilm biomass was evaluated. However, relative no untreated biofilms, no difference in the biofilms following exposure to 10 mM lactate was noted (FIG. 8A).

Biofilms were exposed to increasing concentrations of pyruvate in the absence or presence of pyruvate to ensure PDH-induced loss of the biofilm biomass is due to pyruvate depletion. If PDH induces dispersion by depleting pyruvate, the presence of additional pyruvate would overwhelm PDH and thus reduce the efficacy of PDH in inducing loss of biofilm biomass. Biofilms were exposed to increasing concentrations of exogenously added pyruvate (1-100 mM), in the presence of 10 mM PDH and cofactors. Relative to untreated biofilms, treatment with PDH in the presence of 1 and 10 mM pyruvate significantly reduced the crystal violet-stainable biofilm biomass (FIG. 8B). However, while no difference in the fold reduction of the biofilm biomass was noted in the presence of 1 mM pyruvate, the fold reduction in the biofilm biomass decreased to less than 2-fold in the presence of 10 mM pyruvate. In contrast, no difference in the biofilm biomass was noted in the presence of 100 mM pyruvate relative to untreated biofilms (FIG. 8B). These findings strongly suggest PDH to reduce the biofilm biomass in a manner dependent on pyruvate.

Depletion of Pyruvate Coincides With Dispersion Events

Crystal Violet staining of biofilms in the presence and absence of pyruvate-depleting conditions suggested to significantly reduce the biofilm biomass (FIGS. 7A-B). To determine how exposure to PDH accomplished a reduction in the biofilm biomass, the remaining biofilm architecture was visually analyzed by confocal microscopy. Relative to untreated biofilms, biofilms exposed to PDH were not only characterized by an overall reduced biofilm biomass but by microcolonies having central voids (FIGS. 2E3 and 2F2 ). Void formation has previously linked with biofilm dispersion, a process in which sessile, surface-attached organisms liberate themselves from the biofilm to return to the planktonic state. Overall, more than 60% of the detectable microcolonies present in PDH treated biofilms showed signs of dispersion apparent by central voids (FIG. 2E3 ). In contrast, the vast majority of microcolonies by untreated biofilms were intact (FIG. 2E1 ), with only less than 8% of the microcolonies featuring central void formation (FIG. 2G). Similar results were obtained when biofilms were treated with heat-inactivated PDH (FIG. 2E2 ).

Previous findings suggested microcolonies of P. aeruginosa form hollow voids at their center when they attain a minimum diameter of 40 microns and thickness of 10 microns, with the microcolony size within which these voids form being dependent on the fluid flow rate. Given that exposure to PDH was found to coincide with a larger percentage of microcolonies showing void formation, the effect of pyruvate-depleting conditions on the minimum diameter of microcolonies that disperse was investigated. Analysis of the microcolony size in untreated biofilms suggested that microcolonies having an average diameter of 90 microns were non-dispersed while larger microcolonies having an average size of 210 microns showed signs of dispersion (FIG. 2H). Exposure of biofilms to heat-inactivated PDH (HK_PDH) had little to no effect on the microcolony size of dispersed and non-dispersed microcolonies (FIG. 2H). Moreover, no significant difference in the size of non-dispersed microcolonies following exposure to PDH was noted. In contrast, however, an overall significant increase in the size of dispersed microcolonies of PDH treated biofilms was observed (FIG. 2H). Based on visual observations, the increase in the size of dispersed microcolonies is likely due to “sagging”, with the remaining microcolony structure bulging downward under weight or pressure or through lack of strength.

Overall, these findings suggest exposure of biofilms to PDH and thus, pyruvate depleting conditions to coincide with dispersion events. Considering that PDH treatment does not affect the overall size of microcolonies that remain intact, these findings furthermore suggest that pyruvate depletion enhances dispersion.

Pyruvate-Depletion Induced Dispersion is Independent of Previously Described Factors Contributing to Dispersion

Considering that PDH exposure of biofilms coincided with dispersion events, factors previously demonstrated to be important in the dispersion response following exposure to nitric oxide or nutrients was required for pyruvate-depletion induced dispersion. Specifically, the role of chemotaxis transducer protein BdlA, and two phosphodiesterases, RbdA and DipA, in the pyruvate-depletion induced dispersion response was investigated. The factors were chosen as they appear to play a central role in the dispersion response by P. aeruginosa biofilms, with inactivation of bdlA, rbdA, and dipA impairing the dispersion by P. aeruginosa biofilms in response to various dispersion cues including nutrients, NO, ammonium chloride, and heavy metals (16-18).

Biofilms by strains ΔbdlA, ΔdipA, and ΔrbdA were grown for 4 days in 24-well plates, and subsequently exposed to 10 mU PDH to induce pyruvate-depleting conditions. Biofilms grown in LB but left untreated were used as controls. Following overnight incubation, the remaining biofilm was stained using crystal violet. Relative to untreated biofilms, PDH treatment coincided with a significant loss in the crystal violet-stainable biofilm biomass, with exposure ofΔdipA, and ΔrbdA biofilms to PDH resulting in a >60% loss of the biofilm biomass (FIG. 9A). Under the conditions analyzed, the reduction of the biofilm biomass was comparable or exceeded to the loss noted for wild-type biofilms (FIG. 9A). In contrast, the crystal violet-stainable biomass by ΔbdlA biofilms was only reduced by 2-fold (FIG. 9A). However, the reduction in the biofilm biomass was significant. The reduction in biomass resulting from PDH treatment on strains ΔbdlA, ΔdipA, and ΔrbdA were confirmed visually using brightfield microscopy (FIG. 9B).

Pyruvate-Depletion Induced Dispersion Is Dependent on Lactate Dehydrogenase LdhA and the Microcolony Formation Regulator MifR

These findings suggested that dispersion induced by pyruvate depletion is independent of previously identified factors playing a role in the dispersion of P. aeruginosa biofilms in response to previously described dispersion cues. However, this raised the question of how pyruvate-depleting conditions contribute to biofilm dispersion. The formation of biofilms by P. aeruginosa was previously demonstrated to require pyruvate and pyruvate fermentation, with the biofilm-dependent utilization of pyruvate requiring lactate dehydrogenase LdhA and the microcolony formation regulator MifR. These findings furthermore demonstrated that biofilm formation is associated with stressful, oxygen-limiting but electron-rich conditions, suggesting pyruvate to be required to cope with stressful, oxygen-limiting but electron-rich conditions, referred to as ‘reductive stress’ (too much NADH/electrons, not enough O₂) present in biofilms.

Biofilms by mutant strains ΔldhA and ΔmifR were exposed to PDH, and the biofilm structure of the respective mutant strains exposed to PDH analyzed relative to untreated biofilms, to determine whether the factors contributing to the formation of biofilms by P. aeruginosa also play a role in dispersion. Based on visual comparison, no difference in the biofilm architecture by ΔldhA and ΔmifR in the presence of absence of PDH was noted (FIG. 10A). However, dispersion in response to pyruvate-depleting conditions was restored upon complementation, apparent by biofilms by the complemented strains ΔldhA/pMJT-ldhA and ΔmifR/pJN-mifR demonstrating voids upon exposure to PDH (FIG. 10A).

Visual observations of inactivation of ldhA and mifR showed impaired pyruvate-depletion induced dispersion response, were confirmed using crystal violet staining. Using biofilms by P. aeruginosa wild-type PA14 and corresponding isogenic mutant strains ΔldhA and ΔmifR, no reduction in the biofilm biomass was noted upon exposure of biofilms by the mutant strains ΔldhA and ΔmifR to PDH (FIG. 10B). In contrast, complementation of the ΔldhA and ΔmifR mutant strains coincided with a reduction in the CV-stainable biofilm biomass in a manner similar to the loss of biofilm biomass noted for P. aeruginosa wild-type PA14 (FIG. 10B). These findings strongly suggest exposure to PDH and thus, the pyruvate-depletion induced dispersion response, to require LdhA and MifR. These findings furthermore suggest that dispersion induced by pyruvate depletion may be in response to biofilms no longer being capable of coping with stressful, oxygen-limiting but electron-rich conditions, referred to as ‘reductive stress’ (too much NADH/electrons, not enough O₂) present in biofilms. FIG. 13 shows the effect of 10 mM nitrate under oxic and anoxic conditions, on biofilm crystal violet staining.

Pyruvate-Depletion Induced Dispersion is not Limited to the P. Aeruginosa Laboratory Strain PAO1

The findings suggest that P. aeruginosa biofilms disperse in response to PDH. Given that both P. aeruginosa strain PAO1 and strain PA14 dispersed under the conditions tested (FIGS. 10A & 10B), dispersion in response to PDH was predicted not to be limited to laboratory strains. Instead, three P. aeruginosa clinical strains, isolated from various infection sites, including the urinary tract, burn wounds, and the lungs of cystic fibrosis patients, exhibited dispersion upon exposure to PDH (FIG. 11 ). It is of interest to note, however, that the efficiency by PDH in reducing the biofilm biomass varied between 40-60%. The variability in the extent of the loss of crystal violet-stainable biomass noted for clinical isolates, however, was within the range of the biofilm biomass loss noted for biofilms by the laboratory strains PAO1 and PA14 (FIG. 11 ).

To determine whether dispersion upon depletion of pyruvate is limited to biofilms by P. aeruginosa, two facultative anaerobic bacteria, the Gram-negative bacterium Escherichia coli BW25113 and the Gram-positive Staphylococcus aureus, that represent significant burden on the healthcare system, were used. S. aureus is a major cause of nosocomial and community-acquired infections. E. coli is considered the major causative agent for recurrent urinary tract infections, with E. coli biofilm also being responsible for indwelling medical device-related infectivity. Biofilms by E. coli were grown in 24-well plates, and subsequently exposed to 10 mU PDH. Likewise, biofilms by S. aureus were grown in 24-well plates, and exposed to PDH. Following overnight incubation, the remaining biofilm was stained using crystal violet. Relative to untreated biofilms, PDH treatment coincided with a significant loss in the crystal violet-stainable biofilm biomass, with exposure to 10 mU resulting in a reduction in the biomass of E. coli biofilm while exposure of S. aureus biofilms to 10 mU also resulted on average in a reduction. Dispersion in response to PDH was confirmed by microscopic evaluation of the remaining biofilms. Exposure of S. aureus and E. coli biofilms to PDH and thus, pyruvate depleting conditions, coincided with a reduction in the biofilm biomass relative to the biofilms that were left untreated.

Pyruvate-Depletion Induced Dispersion Coincides With Biofilms Being Rendered Susceptible to Tobramycin

It is well established that planktonic cells are more susceptible to antimicrobial agents than their counterparts growing as a biofilm, and that dispersion coincides with bacteria transitioning to the planktonic mode of growth. Considering that PDH treatment resulted in biofilm dispersion, treatment with dispersion-inducing PDH was investigated to see if it coincides with biofilms being more susceptible to antimicrobial agents. P. aeruginosa biofilms grown for 4 days in 24-well plates were exposed to 100 µg/ml tobramycin in the absence of presence of PDH. Following overnight incubation, the number of viable biofilm cells were determined using viability count. Treatment of biofilms with tobramycin alone resulted in a 2.5-log reduction of the overall biofilm biomass, effectively reducing the number of viable cells from 2.4_(×)10⁸ to 1.2_(×)10⁵ cells per biofilm (FIG. 12A). Tobramycin in the presence of 10 mU PDH coincided with a reduction in the biofilm biomass to 3.5_(×)10³ cells/biofilm (FIG. 12A), with the reduction in the viable cells being equivalent to an overall 5.9-log reduction in the biofilm biomass relative to untreated biofilms. These findings clearly indicate that co-treatment with tobramycin in the presence of pyruvate-depleting conditions resulting in biofilm dispersion, renders the antibiotic tobramycin more effective in killing biofilm cells. Overall, co-treatment enhanced the efficacy of tobramycin by 2.4-logs.

Pyruvate-Depletion Reduces the Biofilm Burden in Porcine Burn Wounds and Enhances the Efficacy of Tobramycin in Killing Biofilm Cells

The data indicate that PDH treatment to induce pyruvate depletion is capable of inducing dispersion of established biofilms and render biofilms more susceptible to the antibiotic tobramycin relative to tobramycin alone. Pyruvate depletion was then investigated in vivo as an anti-biofilm strategy to reduce the bacterial burden of established biofilms, and enhance killing of biofilm cells and thus, reduce or eliminate biofilm-related infections. As P. aeruginosa is considered the 2^(nd) leading cause of biofilm infections, and is one of the principal pathogens associated with wound infections, a wound model of infection was employed. A porcine rather than a rodent model was employed, as pig skin is more similar to human skin, including similar epidermal/dermal-epidermal thickness ratios, dermal collagen, dermal elastic content similar patterns of hair follicles, blood vessels, and physical and molecular responses to various growth factors. Moreover, while rodent models heal primarily by contraction, pig skin heals in a manner similar to human skin by epithelialization. The well-known clinical burn wound isolate P. aeruginosa ATCC 27312 was employed.

Burn wounds were inoculated with 25 µl of a standardized P. aeruginosa suspension harboring 10⁶ CFU/ml and allowed to establish biofilms for 24 h. Infected wounds were subsequently treated daily with 100 and 200 mU PDH in the absence of presence of 100 µg/ml tobramycin. Untreated wounds and wounds only exposed to carrier solution were used as controls. Following 3 and 6 days of treatment, bacterial cells present in wounds were harvested using a flush and scrub technique that separates biofilm bacteria from planktonic bacteria, by flushing the non-adherent (planktonic) bacteria off the wound, followed by scrubbing of the wound to remove adherent biofilm-associated bacteria from the wound bed. Relative to untreated wound biofilms, exposure to 100 mU PDH coincided with up to 2-log reduction in scrub fraction. Similar results for 200 mU PDH (FIG. 12B). Treatment with tobramycin likewise coincided with a 2-log reduction in viable biofilm cells (scrub) relative to untreated biofilms (FIG. 12B). Co-treatment significantly increased the efficacy of tobramycin, apparent by an average reduction in the biofilm CFU/wound of 3.5 and 4-log reduction in the presence of 100 mU and 200 mU PDH, respectively (FIG. 12B). Increased killing of bacteria present in flush in wounds treated with PDH alone and wounds treated with PDH and tobramycin (FIG. 12C) was noted.

The data indicate pyruvate to act as a switch to control biofilm formation, biofilm dispersion, and tolerance, with depletion of pyruvate coinciding with prevention of biofilm formation, disaggregation of existing biofilms, and dispersed biofilms being rendered susceptible to lower doses of antibiotics relative to biofilms.

Pyruvate Depletion is an Effective Anti-Biofilm Therapy, Capable of Controlling And Eradicating Biofilms in Wounds, by Enhancing the Efficacy of Antibiotics and the Immune System

A treatment strategy based on pyruvate depletion has several added benefits. In P. aeruginosa, pyruvate (i) is an energy source, does not promote growth (not a carbon source), and (ii) has only been linked to biofilm growth and long-term bacterial survival under oxygen limiting conditions. (iii) Long-term survival and biofilm studies have not given rise to pyruvate-insensitive mutants. (iv) While pyruvate insensitivity has been noted upon inactivation of genes contributing to pyruvate fermentation (e.g. acnA, ldhA, mifR), these mutants were incapable of coping with the reductive stress and therefore, were unable to form biofilms. (v) Pyruvate depletion by PDH does not affect bacterial growth in liquid or susceptibility of planktonic cells. All of the above lessen the possible selection of pyruvate-insensitive bacteria.

Experimental Procedure

Biofilms were grown in a 24-well plate system modified from the procedure described by Caiazza and O’Toole (2004) to elucidate the role of pyruvate in biofilm formation and biofilm dispersion.

Overnight cultures grown in LB medium were adjusted to an OD600 of 0.05 in fresh 5-fold diluted LB VBMM and grown at 37° C. and rotated at 220 r.p.m. in 24-well microtiter plates at a 45° angle, ensuring that the bottom of the wells is at the air-liquid interface, with the medium exchanged every 12 h.

For biofilm prevention, the growth medium contained 10 mU porcine pyruvate dehydrogenase, cofactors (1 mM b-NAD, 1 mM sodium Co-A, 20 µM thiamine phosphate (TPP)) at the time of inoculation.

For biofilm dispersion, biofilms were first grown for 4 days after which time the growth medium was supplemented with 10 mU porcine pyruvate dehydrogenase, cofactors (1 mM b-NAD, 1 mM sodium Co-A, 20 µM TPP) and allowed to incubate for an additional 16 h.

For susceptibility assays, biofilms were grown as for dispersion assays, but following 4 days of growth, the growth medium was supplemented the aminoglycoside antibiotic tobramycin (100 µg/ml), 10 mU porcine pyruvate dehydrogenase, and cofactors (1 mM b-NAD, 1 mM sodium Co-A, 20 µM TPP). Untreated biofilms or biofilms only exposed to cofactors alone were used as controls.

Differences in the biofilm architecture were visualized by crystal violet staining or microscopy (brightfield, confocal laser scanning). Differences in drug susceptibility were evaluated by viability count.

In vivo biofilms such as those present in porcine burn wounds were found to require increased pyruvate dehydrogenase activity. A pyruvate dehydrogenase activity of 100-200 mU appeared to have maximal activity in dispersing biofilms as well as having maximal adjunctive activity when used in combination with 100 µg/ml tobramycin in eradicating biofilms present in wounds.

Encapsulation of Pyruvate Dehydrogenase

Pyruvate dehydrogenase can be encapsulated in a poly(lactic-co-glycolic acid) (PLGA) particle formulation while maintaining enzymatic activity. PLGA is FDA-approved, degradable, and can protect encapsulated proteins from proteolysis and immune attack.

Pyruvate dehydrogenase-loaded PLGA nanoparticles were made by water-in-oil-in-water double emulsion and had an average size of 360 ± 10 nm and a zeta-potential of -11 ± 3 mV. Based on Western blots, the encapsulation efficiency was approximately 10%. PLGA-immobilization had several benefits:

Free/Unencapsulated pyruvate dehydrogenase was inactive when stored for 2 days at 37° C., yet PLGA-immobilized pyruvate dehydrogenase was still active after 4 days at 4-37° C. PLGA-immobilized pyruvate dehydrogenase was as effective in inducing biofilm dispersion as free pyruvate dehydrogenase (stored at -20° C. until use). PLGA-immobilized pyruvate dehydrogenase particles adhere to biofilm cells.

PLGA-immobilized PDH maintained 100% of its activity when stored for 4 days at -20° C., 4° C., or 20° C. and approximately 75% of its activity when stored at 37° C. (FIG. 15A).

PLGA-immobilized PDH was as effective in inducing biofilm dispersion as free PDH (stored at -20° C. until use, FIGS. 15B, 15E). PLGA-immobilized PDH adhered to peripheral biofilm cells (FIG. 15D), which produce and secrete pyruvate.

An alternative particle substrate is chitosan, a natural, biodegradable polysaccharide with high biocompatibility and mucoadhesive properties. Chitosan nanoparticles were produced encapsulating pyruvate dehydrogenase, formed through ionic gelation. N-trimethyl chitosan chloride (TMC) particles were prepared by ionic crosslinking with tripolyphosphate. Chitosan particles encapsulating pyruvate dehydrogenase had similar activity (ability to convert pyruvate) as PLGA particles.

Therefore, pyruvate dehydrogenase can be encapsulated in a variety of forms, while retaining activity and gaining stability.

Pyruvate dehydrogenase-containing nanoparticles or microparticles may be provided in conjunction with numerous medical applications, including, for example, deposition on medical devices, in wounds or on wound dressings, or as a therapy for cystic fibrosis patients, such as an inhaled micronized or nanoparticle powder inhalant. A nebulizer may also be used for administration.

FIGS. 14A and 14B show the in vivo relevance of the technology. FIG. 14A shows PDH treatment (5 mU) disperses biofilms by clinical isolates, as indicated by CV staining. FIG. 14B shows PDH treatment (5 mU) renders in vitro biofilms by P. aeruginosa and S. aureus and biofilms by P. aeruginosa burn wound isolate ATCC27312 in porcine wounds significantly more susceptible to antimicrobial agents (Ab) In vitro biofilms were treated with tobramycin (150 µg/ml, P. aeruginosa) or vancomycin (100 µg/ml, S. aureus) for 1 h; in vivo wound biofilms were treated with silver sulfadiazine for 1 d. Log reduction refers to reduction in viable cells post treatment. All experiments were done in triplicate.

FIGS. 15A-15F show the effect of PDH nanoparticles (NP) on biofilms. FIG. 15A shows PDH activity, determined spectrophotometrically via NADH conversion, is affected by storage temperature, storage time, and NP encapsulation (NP-PDH). FIG. 15B shows PLGA-immobilized PDH (NP) is as effective in reducing biofilm biomass as free PDH. Biofilm biomass was quantitatively determined by confocal microscopy and COMSTAT analysis prior/post 24 h PDH treatment. FIG. 15C shows an SEM image of NPs, scale bar = 500 nm. (15 D) Confocal images of NPs (red) surrounding biofilm cells (green) FIG. 15E shows biofilm microcolonies (bacteria in green) prior/post dispersion (arrows mark voids indicative of dispersion). FIG. 15F shows PDH-induced dispersion is not affected by excess lactate and pyruvate (≤10 mM), as determined using CV staining of remaining biofilm biomass. PDH, 5 mU. Inset, corresponding CV-stained biofilms post indicated treatment. Experiments done in triplicate.

FIG. 16 shows that nitric oxide (NO) can enhance PDH-induced dispersion of biofilms. Biofilms were grown for 4 days in 24-well polystyrene plates in five-fold diluted LB. Post 4 days, biofilms were either left untreated or exposed to pyruvate dehydrogenase (PDH, 10 mU) or PDH plus 500 uM SNP. SNP was used as a source of nitric oxide (NO). PDH treatment was done in the presence of CoA, ß-NAD+, TPP, and MgSO4. Following 16 h of treatment, biofilms were viewed by confocal microscopy to determine the number of microcolonies showing void formation indicative of dispersion. Number of microcolonies as percent of the total colonies counted per treatment group is shown. All experiments were carried out in triplicate. Error bars denote standard deviation.

FIGS. 17A and 17B shows reduction of biofilm burden in wounds. Second degree porcine burn wounds were infected with P. aeruginosa ATCC® 27312™. Wounds were either left untreated or exposed to pyruvate dehydrogenase (PDH, 200 mU, plus cofactors), silver sulfadiazine cream (SSD), or SSD plus PDH for 24h. Then, bacterial cells were removed from the wounds and the number of viable cells, as shown in (CFU) per wound determined using viability counts. FIG. 17A shows the number of bacterial cells present in wounds. FIG. 17B shows the Log₁₀ reduction was determined relative to untreated biofilms (based on data shown in FIG. 17A). Experiments are representative data obtained using 3 wounds per treatment group (n=3). Error bars represent standard deviation. Pretreatment with PDH and SSD should have ability to prevent infection.

Encapsulated PDH demonstrates improved thermal stability. The specific depletion of pyruvate can be accomplished enzymatically using pyruvate dehydrogenase (PDH) or lactate dehydrogenase (LDH). PDH requires NAD⁺ and CoA as cofactors to enzymatically convert pyruvate to acetyl-CoA while LDH requires NADH to convert pyruvate to lactate. PDH is preferred over LDH for three reasons: (i) NAD⁺ is more stable than NADH, (ii) wound exudates have been reported to contain ≥10 mM lactate (but low pyruvate and no acetyl-CoA) with the presence of lactate likely resulting in LDH producing pyruvate in vivo, rather than depleting it (since LDH is reversible), and (iii) PDH is not inhibited by the presence of lactate (FIG. 15F). However, most if not all enzymes are relatively unstable and rapidly lose activity when exposed to temperatures relevant to in vivo applications (body temperature = 37° C., FIG. 5A). Free PDH is no exception and is rendered inactive within less than 1 day when stored at 37° C. (FIG. 5A).

PLGA particles can be formulated with varying PLGA molecular weight, synthesis method, and the loading of PDH. The PLGA molecular weight affects the crystallinity, hydrophobicity, and degradation rate of the particles—factors likely to affect PDH stability over time. NPs may be synthesized using either a water-in-oil-in-water (W/O/W, FIG. 15C) double emulsion method or nanoprecipitation method.

W/O/W Synthesis: for a 1× batch, 400 µl of concentrated porcine PDH (Sigma Aldrich, 5.8 mU/µl) in phosphate buffered saline MOPS is rapidly mixed with 4 ml of acetone containing 100 mg PLGA (either 38 kDa or 60 kDa) and sonicated for 40 s. The solution is then added to 8 ml of 0.1% v/v polyvinyl alcohol solution with sonication. The emulsion is diluted, acetone is evaporated, and unencapsulated PDH is removed via centrifugation. Particles are frozen and freeze dried.

Nanoprecipitation Synthesis: In particle synthesis, the avoidance of solvents with potential effects on protein integrity is desirable and may increase the activity of encapsulated PDH. Formulations are created by by nanoprecipitation using glycofurol 67.68, which has low toxicity 69-74. PDH (100 µL) is added to 300 µL of 12% PLGA (38 kDa or 60 kDa) in glycofurol and mixed with 100 µL of ethanol and 1.5 mL of 1% Poloxamer 188. Particles are centrifuged, frozen, and freeze dried.

Chitosan NPs: While PLGA has been used extensively in drug delivery applications and has successfully delivered several proteins without substantial loss of activity and worked well in preliminary experiments, the breakdown of PLGA into its acidic constituents can potentially cause protein instability. As an alternative, chitosan is a natural, biodegradable polysaccharide with high biocompatibility and mucoadhesive properties. Chitosan NPs have been used for encapsulation of proteins and can be simply formed through ionic gelation. N-trimethyl chitosan chloride (TMC) particles may be prepared by ionic crosslinking with tripolyphosphate. Chitosan particles may be formulated with the following variables: chitosan molecular weight (low and medium, Sigma) and PDH loading.

PEGylation of particles: The widely used biocompatible polymer PEG may be incorporated to increase the hydrophilicity of the NP to preserve the biological activity of PDH38 and to render the particles less likely to be immunogenic. In order to avoid affecting the activity of already encapsulated PDH, PEG-5k may be be linked to the already-synthesized particles’ surface. Carbodiimide chemistry (EDC/NHS) may then be used to create a bond between an amine group on PEG (mPEG5k-NH2) and PLGA-COOH 32. For chitosan particles, a carboxylic acid group on PEG (mPEG5k-COOH) bonds an amine on the chitosan that is present after reducing the C=N with NaBH₄.

Wound temperatures have been reported by Shorrock et al. to range from 32-41° C. Furthermore, wounds have been shown to be a proteolytic environment and to have an average pH of 7.1-7.5, with measurements taken at the wound center indicating an average pH of 7.6±0.6 and areas on the epitheliated wound borders showing physiological pH values of 5.9±0.4.

While free PDH activity decreases significantly upon storage, PLGA-encapsulated PDH remains active for 4 days (FIG. 15A).

PLGA-encapsulated PDH adheres to biofilm cells (FIG. 15D). This characteristic may be important for effective biofilm dispersion (FIG. 15E, compare 10 mU PDH to PDH-NP-induced dispersion response).

Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow. 

1. A composition for inducing a dispersion of sessile organisms within a biofilm in an aqueous medium, comprising an enzyme adapted to deplete pyruvate in the aqueous medium, within an extended release reservoir or extended release formulation, configured to release the enzyme over a sufficient duration to induce hypoxic stress and a result a dispersion response of the sessile organisms within the biofilm.
 2. The composition according to claim 1, wherein the depletion comprises enzymatically altering the pyruvate by addition of a purified enzyme to the aqueous medium.
 3. The composition according to claim 2, wherein the enzymatically altering comprises decarboxylation.
 4. The composition according to claim 2, wherein the enzymatically altering comprises phosphorylation.
 5. The composition according to claim 1, further comprising cis-2-decenoic acid.
 6. The composition according to claim 1, further comprising nitric oxide.
 7. The composition according to claim 1, further comprising an insoluble matrix configured to absorb pyruvate.
 8. The composition according to claim 1, wherein the depletion comprises chemically transforming the pyruvate to another chemical species.
 9. The composition according to claim 1, wherein the depletion comprises an imine-forming reaction.
 10. The composition according to claim 1, wherein the enzyme comprises pyruvate decarboxylase.
 11. The composition according to claim 1, wherein the composition comprises a pyruvate fermentative organism which produces the enzyme.
 12. The composition according to claim 1, wherein the enzyme is selected from the group consisting of purified pyruvate dehydrogenase; purified pyruvate oxidase; purified lactate dehydrogenase; and a purified transaminase.
 13. The composition according to claim 1, further comprising an antibiotic biofilm.
 14. A method of treating a biofilm, comprising administering to a subject having a biofilm-associated infection, a formulation comprising a stabilized enzyme having a pyruvate substrate specificity, under conditions effective for reducing environmental pyruvate and causing a sufficient hypoxic stress of cells associated with the biofilm-associated infection to induce a dispersion response.
 15. The method according to claim 14, further comprising administering a bacterial biofilm dispersion inducer to the subject.
 16. The method according to claim 14, further comprising administering an antibiotic to the subject, wherein an antibacterial activity of the antibiotic is enhanced by the dispersion response.
 17. The method according to claim 14, wherein the biofilm-associated infection is associated with at least one of a burn, dental plaque, dental caries, gingival disease, an oral infection, a lung infection, and acne.
 18. The method according to claim 14, wherein said administering is carried out with at least one of a lotion, cream, ointment, gel, an inhaler, and a nebulizer.
 19. A composition, comprising a stabilized enzyme which retains at least 50% of its initial activity for 48 hrs after hydration at 37° C. to a concentration of at least 1 mU/ml, effective for reducing pyruvate concentration in an aqueous solution to exert a hypoxic stress on sessile organisms in a biofilm exposed to the aqueous solution.
 20. The composition according to claim 19, further comprising at least one of cis-2-decenoic acid, an antibiotic, and a source of nitric oxide, wherein the stabilized enzyme comprises at least one of a purified pyruvate decarboxylase, purified pyruvate dehydrogenase; purified pyruvate oxidase; purified lactate dehydrogenase; and a purified transaminase. 